fixes ceph_stable_release logic mentioned in issue #446

fixes ceph_stable_release logic mentioned in issue #446

I changed the argument used for starting the mds server. (pre
infernalis)
```
service ceph start mds
```
errors, while
```
service ceph start mds.$hostname
```
correctly starts the service.

I changed the mds directory ownership from ceph:cephh to root:root
again, for pre-infernalis.

And finally, add the ceph_stable_releases checks for the upstart
activation task `for or after infernalis release'.