API: system hooks API functions and documentation updated

* updated system hooks documentation and code comments
* fixed access to system hooks if no user given resulting in a `500 Server Error`
* added tests
Merge branch 'master' into api/system_hooks_adjustments
Move groups and teams to tabs on dashboard. Remember tab with cookie
Group and team rss is valid now
add coveralls.io to travis builds
fixed travis env, added coverage badge
Merge pull request #3170 from Asquera/api/system_hooks_adjustments

API: system hook request functions and documentation updated
Rename to coffee.
Reduce amount of user info provided with internal api
Covert to coffee.
fix api internal test
Merge pull request #3192 from hiroponz/convert-to-coffee

Convert branch-graph.js to branch-graph.js.coffee
restyle and cleanup emails
Search projects on dashboard was not worked. Fixed
Search fields were have same id's. Fixed
Tests improved
Use gitlab-shell to move repos. Requires gitlab-shell v1.1.0
fix project move email
check gitlab-shell version in gitlab:check
Tests for dashboard projects fixed