Make the first branch pushed to an empty repository the default HEAD

In an empty repository, pushing a new branch not called "master" would leave HEAD in an unknown state, causing ambiguity if another branch were pushed. This could in turn cause a new protected branch to be created and cause the default branch to change.

* Closes #1561
* Closes #1576
* Closes https://github.com/gitlabhq/gitlabhq/issues/8883

See merge request !614

Add Markdown feature specs for markup inside links

It was already working, just want to make sure we don't break it in the future.

See merge request !619

It was already working, just want to make sure we don't break it in the
future.

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

Refactor mr form

* re-use issuable form for new mr page
* small UI improvements to MR compare and new pages

See merge request !616

Small UI improvements to make project sidebar more neat

* make sidebar blocks more compact
* make clone panel smaller for better aspect ratio
* make `forked from` section cleaner

Screenshot:

![Screenshot_2015-05-06_16.42.12](https://gitlab.com/gitlab-org/gitlab-ce/uploads/69723db619ae7ae4d9551f6340d45384/Screenshot_2015-05-06_16.42.12.png)

cc @rspeicher

See merge request !617

Single docker image

See merge request !1805

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>

Allow to configure smtp and sendmail in gitlab.yml

When use change branches link at MR form - save source branch selection instead of target one

Fix for https://dev.gitlab.org/gitlab/gitlabhq/issues/1800

cc @jacobvosmaer

See merge request !615

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

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

In an empty repository, pushing a new branch not called "master" would
leave HEAD in an unknown state, causing ambiguity if another branch
were pushed. This could in turn cause a new protected branch to be
created and cause the default branch to change.

* Closes #1561
* Closes #1576
* Closes https://github.com/gitlabhq/gitlabhq/issues/8883

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