orchestration: Add test for resource_registry environment

Adds support for passing files argument to the create/update
calls in the json client, and adds a simple test of defining
a provider resource, which is a user-defined resource type,
mapped via the "resource_registry" section of the environment
file, with the filename looked up by a key in the files map.

Change-Id: I87fd1f2b1cf2c68c22d53891d99c8cd6b6b7c777
Partial-Bug: #1317095
Merge "orchestration: Add test for resource_registry environment"