Use pre-wrap for diff code in discussion view

This prevents merge request comments from being hidden in discussion view.  See #2017.

### Before

![diff_comment_before](https://dev.gitlab.org/Okada/gitlabhq/uploads/e6d24987b8d88f4e8a5883645d569b56/diff_comment_before.png)

### After

![diff_comment_after](https://dev.gitlab.org/Okada/gitlabhq/uploads/fc035f9fc44718dc8424d3f8b54f0953/diff_comment_after.png)

This change doesn't affect the "Changes" tab:

![diff_view_comment](https://dev.gitlab.org/Okada/gitlabhq/uploads/9975d4c3feac629d6a0d76b5a0ef43d8/diff_view_comment.png)

cc @sytse

See merge request !1700

Fix typo

Restyle import

Render import providers in one line and make it buttons

See merge request !1699

More flatly

* use sass variables for repeating colors
* use more of Flatly theme variables
* refactor buttons

See merge request !1698

Unblock user if they were unblocked in AD.

Fixes problem with !1687.

See merge request !1694

Fix typo in CHANGELOG.md

Fix failing tests

Revert the last merge, as it breaks the master and I didn't see that this line is used in hooks as well when I merged this.

See merge request !390

This reverts commit 07f9a3f9, reversing
changes made to 48036751.

Reverted this because the data is used in hooks as well.

Follow on to MR 376

Follow-on to MR 376 from @haynes . Remove unnecessary fetch of commit messages for initial push. This will reduce the memory usage significantly.

See merge request !387

Bump gitlab_git to 7.1.1

Verify found object is actually a commit in Commit.find.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/1204

See merge request !1696

Minor cleanup around UTF-8 encoding.

Minor cleanup to be merged after https://dev.gitlab.org/gitlab/gitlab_git/merge_requests/24 is merged in.

See merge request !1642

Verify found object is actually a commit in Commit.find

Execute hooks and services when branch or tag is created or deleted through web interface.

Fixes #2095.

Split up into commits to make it easier to see why what was changed :)

See merge request !1692