Adapt to package renames for grizzly and newer installs.
Stripping out obsolete code from the compute recipe.
Provide additional ways to configure vms to use ceph.

We currently install vms-rados when the ceph_config key is non
nil. One can easily install ceph and use VMS without providing
ceph_config, as VMS uses a sane default.

In this change we add some optional vms sysconfig attributes for
setting rados/rbd pools and prefixes and automatically update the
memory and disk urls based on these attributes when they are
provided. With this, all a user has to do to configure vms to use
ceph is create the rados and rbd pools and provide the pool names
and the optional prefixes through the chef attributes.
Clean up library helper functions.

Mixing helpers into the chef recipe class rather than the apt
repository class. Updating a couple of bits to use existing helpers
and refactoring the distro to repo mapping to a helper function.
Updating default VMS_CACHE path to /dev/shm.