Change test_utils.make_im to accept options for DummyApi
Move im.msg assignment to InteractionMachine.setup()
Add tests for test_utils.make_im()
Only set defaults when opts.api is not a DummyApi for test_utils.make_im()
Add docs for test_utils
Merge branch 'develop' into feature/issue-131-allow-test-utils-make-im-to-accept-options-for-dummyapi

Conflicts:
	lib/test_utils.js
	test/test_test_utils.js
Merge branch 'feature/issue-131-allow-test-utils-make-im-to-accept-options-for-dummyapi' into develop