Update databases.md

run mysql_secure_installation to secure the freshly installed mysql server
Merge pull request #4891 from denics/patch-2

Add mysql_secure_installation to databases.md
Update gitlab
Merge pull request #5241 from earlonrails/patch-1

Update app version in init script
Backport init script because it is much better.
Merge branch 'backport-init-script' of /home/git/repositories/gitlab/gitlabhq into 6-0-stable
Merge branch '6-0-stable' of github.com:gitlabhq/gitlabhq into 6-0-stable