Merge pull request #1712 from riyad/use-gem-for-emoji

Use gem for Emoji
add shared repository doc.
Fix wrong parameter order in Team#team_member_by_name_or_email
Add CommitDecorator#author_link
Update author info in tree view
fix ambiguous entry in changelog
fix mass-assignment error in user create API
fix typos in specs
fix wrong test case
name and password_confirmation not required to create a user via API
update API docs
fix typo in spec
cleanup main.coffee
use 'js-' prefix for behavioral 'gfm-input' class
cleanup coffeescript code for mentions auto-complete
remove unnecessary loader.js
merge graph.js into projects.js
remove unnecessary snippets.js
enable Oauth login for existing regular users

fix: https://github.com/gitlabhq/gitlabhq/issues/1620
Refactor Gitlab::Merge

* Refactor and document methods
* Rename merge to merge!
* Fixes #1544