Add a missing mock to rackspace cloud server test

A few tests were missing a mock call, which led the tests into an
infinite loop

Change-Id: I66ba612ec2d7eec561f6a0de97e7d3811fbd1f60
Closes-Bug: #1252333
Fix long server name in Cloud Servers test

Make server name in test_cs_update_cfnuserdata_nonzero_exit_status()
less than 53 characters or else it will be truncated and not match what
mox expects.

Change-Id: I4fde4824dce2cc2b8d6e8879a50fc5022930b789
Closes-Bug: #1253178
Make Rackspace CloudServer inherit from Resource

Very little was being inherited from Instance.  Moved the common bits
into nova_utils.

Change-Id: Ib22cd1380b1256ac5695b223a321203924dda1e9
WIP

Change-Id: I312ddc25e02843b0116b8a2cb88defef05ca88ac