Merge branch 'master' into non-interactive-aws-install

Conflicts:
	doc/installation.md

Fix merge mess in installation.md

2. SSH Keys Help page

* don't show pointer cursor for for the whole list item any more
* fix hover color for links in .row_title

* .page_title  class added. Used for better page headers
* improved help page
* added back links for help pages
* show app version & revision on help page

Backend changes:
* Gitab::Version && Gitlab::Revision constants