Tests cephfs and radosgw

This PR enables cephfs and radosgw testing in the AIO recipe.
#121 fixes creating the radosgw key by creating a random mon secret
#122 fixes radosgw on Debian

Outstanding problems that I've found:
- CentOS 6 doesn't have cephfs compiled into the kernel. I see that there are packages that probably have it.
- Fedora 18 test-kitchen doesn't have a mod_fastcgi package, where does it come from?
- Ubuntu 14.04 doesn't install the ceph-mds package by default, it is marked as Recommended