Fix some grammatical issues

Ci status for merge requests index page

![ci-mr-index](/uploads/1424564c87ac6ff5fb2c4bc260fbebdf/ci-mr-index.png)


See merge request !1682

[ci skip]

Add missing character

This adds the missing character `a` to the help-text

Added missing period in gitlab_flow article.

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

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

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

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

Add "Copy to clipboard" buttons

See #2855

See merge request !1494

Use git follow flag for commits page when retrieve history for file or directory

This can be really helpful when you want commit history for file that was moved recently
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1680

Fix CI regressions

This MR fixes a couple of small CI regressions
- Allow developer to manage builds
- On CI Admin page show only projects that are present in GitLab
- On Runner CI Admin page show only projects that are present in GitLab
- Refresh build log only when status changes
- Show the oldest builds on top when viewing Builds - it most cases it shows running builds on top
- Fix Lint rendering
- Fix number of other builds in build widget

Fixes #3164

Fixes #3161 

Fixes gitlab-org/gitlab-ci#343

See merge request !1679

Adds buttons to the commit list SHAs and the cross-project reference
data on issuables.

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

Fix cloning Wiki repositories via HTTP

Cloning a project Wiki over HTTP would end up cloning the main repository
since the .wiki extension was being stripped.

Closes #3106

See merge request !1676

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

Update SourceSansPro fonts
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1678

Fix: Inability to reply to code comments in the MR view, if the MR comes from a fork

https://dev.gitlab.org/gitlab/gitlabhq/issues/2535

See merge request !1675

Fix API::APIHelpers -> API::Helpers again for master

Rails Autoload find file to require is use , APIHelpers -> api_helpers.rb, not helpers.rb;

Cloning a project Wiki over HTTP would end up cloning the main repository
since the .wiki extension was being stripped.

Closes #3106