Add 6.0-to-6.2 update guide
Include a note if there are security fixes.
Merge branch 'security-upgrade' of /home/git/repositories/gitlab/gitlabhq
Bump gitlab-shell to 1.7.3
Merge branch '6_0_to_6_2' of /home/git/repositories/gitlab/gitlabhq
Merge branch 'master' of github.com:gitlabhq/gitlabhq