Run bin/qa from anywhere

Also reverts https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16824 since it's no longer required.

gitlab-ce qa/rs-qa-from-anywhere % pwd
/Users/rspeicher/Code/gitlab/gdk-ce/gitlab-ce
gitlab-ce qa/rs-qa-from-anywhere % qa/bin/qa Test::Instance http://localhost:3000
Run options: include {:core=>true}

Randomized with seed 20328
^C
RSpec is shutting down and will print the summary report... Interrupt again to force quit.