New doc about creating groups

I added a new document about creating groups in GitLab.

I also fixed comment in previous MR https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1885


See merge request !1886

Conflicts:
	doc/install/requirements.md

Compress database backup

Restore handles both cases: uncompressed and compressed backup. As an improvement `IO.popen` can be used.

/cc @jacobvosmaer

See merge request !873

API to set application settings for admin
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !934

Detail too many warning to explain that merge will still work.



See merge request !1889

Return 40x error codes if branch could not be deleted in UI

### What does this MR do?

This MR makes `BranchesController` return the proper status code in case of a failure to delete a branch.

### Why was this MR needed?

Deleting a branch would always return status 200, even if the branch could not be found or deleted for some reason. This was confusing because while trying to debug an issue with encoded slashes, it looked like the deletion was successful when it had failed.

### What are the relevant issue numbers?

This issue was uncovered in #1804

See merge request !823

Add ref switching support for graphs

It is now possible to view contributor and commit statistics for
refs beyond the default branch. While the Git ref already was part of
the path it has not been used before.

Additionally, the code in RefsController#switch has been slighliy
refactored since it would have become confusing with additional if-else
branches added.

See merge request !932

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

It is now possible to view contributor and commit statistics for
refs beyond the default branch.

Additionally, conditions in RefsController#switch have been refactored
in order that a `case` block is used now.

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

Use teaspoon instead of jasmine:ci

Disable sticky diffs

Revert feature introduced in https://github.com/gitlabhq/gitlabhq/pull/8760

Why?

* It has unfixed bug for long time which is really annoying - https://github.com/gitlabhq/gitlabhq/pull/8760
* I was not able to properly fix it
* It affected performance in bad way

See merge request !935

Audit log for user authentication

https://dev.gitlab.org/gitlab/gitlabhq/issues/2318

See merge request !931

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

This reverts commit af44c650.

Add Irker service configuration options

### What does this MR do?

This MR makes a number of hard-coded Irker parameters configurable in the service settings: Irker server host, port, and default IRC URI. It also removes the "max recipient" limit since the recipient list is configurable only by the project owner, and it makes no sense to update the limit when it is implied in the recipient list already.

### Why was this MR needed?

The existing service assumed that gitlab.com was running an Irker daemon on `localhost` when it was not. Using Irker on gitlab.com thus did not work at all. This MR allows users to provide their own Irker daemons.

### Are there points in the code the reviewer needs to double check?

My main concern is whether allowing a user to specify the server/port combination would have security implications for a host. Given that HipChat and Slack allow users to do this, I didn't think this was doing anything novel.

### What are the relevant issue numbers?

* Closes #1713
* Closes #1714
* Closes gitlab-com/support-forum#139

### Screenshots

### Before

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/2eb3eb815e249e9fb669fc97ecd4f3c8/image.png)

### After

![image](https://gitlab.com/gitlab-org/gitlab-ce/uploads/cceaba951c05bd3df2c842cc68046b87/image.png)

See merge request !930

fixed link to gitlab-basics

Fixed link to gitlab-basics

See merge request !1887

Improve documentation of lists in Markdown

See merge request !899

Closes #1713
Closes #1714
Closes gitlab-com/support-forum#139

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

Allow user to be blocked and activated via the API

When authenticating against LDAP if a user has been disabled in LDAP they can no longer log on to the website or commit over http(s) but will be able to commit using any ssh keys.  This functionality allows us to look for users in GitLab that no longer exist in LDAP and disable then in GitLab.

Closes Feedback item: [Add administrative API call to block users](http://feedback.gitlab.com/forums/176466-general/suggestions/4098632-add-administrative-api-call-to-block-users)

See merge request !587

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