Create objects using request body rather than model object

[chouseknecht]

• Create objects by passing body=request_dict, rather than a model object. This seems to allow the API to insert defaults for things the user did not specify. Follows the create deployment example.

• Adds use of dictdiffer to return a list of differences when comparing two objects. Useful for debugging.

• Fixes broken idempotents discovered during Ansible module testing. Issue was setting object properties of type list to [] rather than None.

• During exception handling for CRUD operations, check if the exception body startswith('{') before attempting to convert it to JSON. If the exception is related to an authorization problem , for example, it won't contain JSON.