orchestration api refactor access to stack outputs

Refactor test_server_cfn_init access to stack outputs so it uses
a new wrapper which gets the stack and returns the requested
output.  This provides a useful function which can be used in
other tests which parse the stack output.  Since we no longer
need to get the stack in test_server_cfn_init, remove the gets
and duplicate checks for CREATE_COMPLETE.

Change-Id: If1d0990ac9467b6e9778e4444b2ec5fc0f1e44e7
orchestration api add basic volume resource test

Adds a basic test which provides coverage for the OS::Cinder::Volume
resource, we just create and delete a volume and check the stack
details match those obtained directly via the cinder API.

Change-Id: Ia096f99c0c5decfafc144fe5afb47b6c871a218d
Merge "orchestration api refactor access to stack outputs"
Merge "orchestration api add basic volume resource test"