Merge branch 'web-editor-autocrlf' into 'master'

Convert CRLF newlines to LF when committing using the web editor.

Fixes #1823 and https://github.com/gitlabhq/gitlabhq/issues/7950.

Depends on https://gitlab.com/gitlab-org/gitlab_git/merge_requests/29 being merged and a new gitlab_git being released.

cc @jacobvosmaer

See merge request !858