Add unit test for creating structured SW Config
Add unit test for creating structured SW Config

All of the existing unit tests for the software config service assume the
'config' part is a string; add a test where the config is a dict, as in
OS::Heat::StructuredConfig, to ensure that this doesn't break.

Change-Id: I2abcaae952890e206857363d34f976e04937f324

openstack/heat,openstack/heat