This syncs most of the common files with the openstack-tests repository.
This effectively removes the Ubuntu 14.04 support from the Vagrantfile
as well as the RHEL6 STIG V-38496 workaround for it. This also removes
the now unused tests/vagrant.yml file and uses the tests/test.yml like
the upstream OpenStack CI does.
However, it doesn't sync the bindep.txt file since it doesn't quite
match what we have in the openstack-ansible-tests repository so the
shared one needs to be fixed first.
Finally, it adds a new doc/.gitignore file to exclude the generated
documentation file. This is necessary in order for the shared .gitignore
one to be used in the root of the repository.
Change-Id: Ia34979af9029ffb03fb525679356e6d9f3a039a6
1a02653708