Fix a trailing new line

The "How to Merge" modal included a trailing new line in the code
block. This commit removes that disfigurement.

Fix missing button types

Improve project home page usability

I looked at project page and saw next problems with it:

* a lot of information but not separated on blocks - hard to understand
* unclear how to contribute to project

Instead of complete redesign I followed step-by-step changes.

### Step 1

First of all I separated Repository and Contribution blocks.
Contribution block should makes it easy for people to contribute. Even when we visit GitHub project page its not clear how to start. Our Contribution section should help with it. All repository stats and download button moved to Repository block.

![Screenshot_2015-05-05_11.49.16](https://gitlab.com/gitlab-org/gitlab-ce/uploads/e69977603acfdc381acb539b19e8cba1/Screenshot_2015-05-05_11.49.16.png)

### Step 2

Next step was to make top section less loaded. I moved clone panel to sidebar because it is very heavy element and rarely used. If you use web editor - you dont even use it. If you work via http/ssh you will copy remote only once. So my idea - it should be on home page but should not be in center of attention.

![Screenshot_2015-05-05_12.47.04](https://gitlab.com/gitlab-org/gitlab-ce/uploads/41633cc8915bb12c979230567b40aea4/Screenshot_2015-05-05_12.47.04.png)

See merge request !610

Use the configured display name in e-mails from Devise mailer

By default, it is set to "GitLab", but a user may configure the display name to something else.

See merge request !613

Improve help line for restricted domain signups

The setting may be misconstrued as only allowing access from certain domains. Add help to clarify this applies to e-mail domains.

See merge request !612

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>

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>

Fix CI links on MR page

Fixes gitlab-org/gitlab-ci#145

See merge request !609

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>

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>

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

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

Docker: update omnibus package

See merge request !605

Update spelling in comments in authentication.rb

Improve documentation of configuring external issue trackers

There was some confusion over the deprecated `:issues_tracker_id` field. Added documentation.

Closes #1514

See merge request !580

Closes #1514

correct spelling

Added " How to maintain tight control over the number of active users..."

Added " How to maintain tight control over the number of active users on your GitLab installation" to documentation.

Please check that documentation is OK before accepting Merge. I took if from https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/gitlab.yml.example#L149

cc/ @sytse

See merge request !1792