Disable internal issue tracker if external tracker in use

### What does this MR do?

This MR disables routes to the internal issue tracker if an external issue tracker (e.g. Redmine) is in use. A 404 page is returned if a user attempts to access any of the issue routes.

### Why was this MR needed?

Enabling the external issue tracker would still keep the internal one active, which would lead to odd behavior where users could create issues but not close them.

### What are the relevant issue numbers?

Closes #2006

See merge request !993

Set max-width for README, issue and merge request description

It allows easier text reading on big screens

### Problem

Text is hard to read on wide screens:

![Screenshot_2015-08-14_11.33.39](https://gitlab.com/gitlab-org/gitlab-ce/uploads/2bdb092c09495c7aa94b0589df4b7e65/Screenshot_2015-08-14_11.33.39.png)

### Solution

Set max-width to content. Screenshots:

![Screenshot_2015-08-14_11.31.54](https://gitlab.com/gitlab-org/gitlab-ce/uploads/00cd7a77b81b30458a1675ec562d7463/Screenshot_2015-08-14_11.31.54.png)
![Screenshot_2015-08-14_10.53.16](https://gitlab.com/gitlab-org/gitlab-ce/uploads/4756f87a3bbb7179e55b1c8f8ee40459/Screenshot_2015-08-14_10.53.16.png)
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1161

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

It allows easier text reading on big screens
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fix: User search feature in admin area does not respect filters

https://dev.gitlab.org/gitlab/gitlabhq/issues/2482

See merge request !1155

Fix changelog

New doc about how to add an image in GitLab Basics

See merge request !1918

Time for 7.14.0.pre

Provide more feedback what went wrong if HipChat service failed test

This MR adds support for displaying the error message during HipChat service test. Before an Error 500 would be displayed with no helpful remarks.

Screenshot:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/10f82eb02db138f9680e69cdb3d3ed82/image.png)

Issue gitlab-com/support-forum#213

See merge request !1144

Bring clone bar back

Screenshot:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/5198a110c1f1bfd5b6b050b648e8ad45/image.png)

See discussion in !1080

See merge request !1147

Update changelog

See merge request !1153

Note query information

See merge request !1149

markup_helper: detect .mkd and .mkdn as markdown

See merge request !1148

This reverts commit 4c586dc7.

See discussion in !1080

Move merge manually text below merge widget 

Replace !1121 

Screenshot: 

#### Before

![Screenshot_2015-08-10_18.25.22](https://gitlab.com/gitlab-org/gitlab-ce/uploads/ac7df8dd03104b3b44c61b3bff709653/Screenshot_2015-08-10_18.25.22.png)


#### After

![Screenshot_2015-08-10_18.28.30](https://gitlab.com/gitlab-org/gitlab-ce/uploads/c92b8eaeadb842705577dba1f52b67e5/Screenshot_2015-08-10_18.28.30.png)



See merge request !1141

Issue gitlab-com/support-forum#213

Add merged label on branches page

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add "Check out branch" button to the MR page.

I appreciated the thought behind adding the "Fetch this branch using ..." line, but not so much the implementation. I think a "Check out branch" button alongside the existing "Download as" makes more sense to get instructions on how to get the changes on your local machine, since that's pretty much what "Download as" does as well. 

Like the "command line", the button opens the command line merge instructions modal. I've improved the text of that modal in !1120.

![Screen_Shot_2015-08-08_at_22.10.19](https://gitlab.com/gitlab-org/gitlab-ce/uploads/fd185df012e9759dfea198ed9fa3f80f/Screen_Shot_2015-08-08_at_22.10.19.png)

It looks even better in combination with !1121, which gets rid of the "If you want to ..." line:

![Screen_Shot_2015-08-08_at_22.10.55](https://gitlab.com/gitlab-org/gitlab-ce/uploads/3fa469d0e2bd4e3ec4992ffa5864c718/Screen_Shot_2015-08-08_at_22.10.55.png)

cc @dzaporozhets @rspeicher 

See merge request !1116

Improve merge request widget

Return merge request widget improvements that were reverted with satellites

See merge request !1140

Improve text of MR merge widget and manual merge modal

Modal with manual merge instructions:

![Screen_Shot_2015-08-08_at_21.30.23](https://gitlab.com/gitlab-org/gitlab-ce/uploads/2bffe42e9ad76afd02efbe5816027767/Screen_Shot_2015-08-08_at_21.30.23.png)

Archived:

![archived](https://gitlab.com/gitlab-org/gitlab-ce/uploads/e1efa1d54ce7ead8de6e88ca34095c09/archived.png)

WIP:

![wip](https://gitlab.com/gitlab-org/gitlab-ce/uploads/14a831458d0946722559ec643f91678c/wip.png)

Missing target branch:

![missing_branch](https://gitlab.com/gitlab-org/gitlab-ce/uploads/340083bbacbc234906e58cf76c586a9e/missing_branch.png)

Missing source branch:

![missing_branch_source](https://gitlab.com/gitlab-org/gitlab-ce/uploads/72f80ed58efed88b2bbcf403b55b1a01/missing_branch_source.png)

Nothing to merge:

![nothing](https://gitlab.com/gitlab-org/gitlab-ce/uploads/85b0d9da87acacd53cffd0df58d8eed4/nothing.png)

Checking ability to merge:

![check](https://gitlab.com/gitlab-org/gitlab-ce/uploads/32d75322e622025610c446e8ca7d892d/check.png)

Conflicts when allowed to merge:

![conflicts](https://gitlab.com/gitlab-org/gitlab-ce/uploads/23fdb2c60a27d873b3cc8a008203eb59/conflicts.png)

Conflicts when not allowed to merge:

![conflicts_not_allowed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/113462a80fc65bf48b20dc0efd808363/conflicts_not_allowed.png)

Mergeable when allowed to merge:

![accept](https://gitlab.com/gitlab-org/gitlab-ce/uploads/1b3bb1a71df21728fe9318e7a083bfba/accept.png)

Mergeable when not allowed to merge:

![not_allowed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d38fa5c96f8f9d7223bb6bc7ad36f29d/not_allowed.png)

Merge in progress:

![locked](https://gitlab.com/gitlab-org/gitlab-ce/uploads/b60dcf5eb70e6032b0e8aac766018df3/locked.png)

Merge failed:

![failed_2](https://gitlab.com/gitlab-org/gitlab-ce/uploads/3713b9a10298183935b028b658271ac9/failed_2.png)

Merged:

![merged](https://gitlab.com/gitlab-org/gitlab-ce/uploads/7f68a48dd197a71351c9a80c59c8ecbe/merged.png)

Closed:

![closed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d5ce040449b7db943bd2fbfffb607a10/closed.png)

cc @dzaporozhets @rspeicher

See merge request !1120

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Bump Haml to 4.0.7 to speed up textarea rendering

The current regexp caused long load times when textarea blocks were surrounded by whitespace. This fix has been submitted to the Haml library and passes tests there:

https://github.com/haml/haml/pull/850

Closes #1987

See merge request !984

Fast blame

Improve performance for file blame page. Also bring some small UI improvements

See merge request !1129

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>