This patch updates the installation doc for the devstack plugin. It
also removes the Vagrant option as it has not been maintained in quite
some time.
Change-Id: I97fc2fac0cb29b1059b668bbe817a2778a8a4a70
This makes usage of barbican in devstack significantly more straight
forward. No more pre-cloning and moving files around.
Change-Id: I0ec63819b3aae21a6ffaed5cf8285e26dce6ae94