-Create collection now raises a CreationError when create fails rather than returning false.
-Search Subscribers now acceptions hashes passed in for custom_fields value.
CreateSubscriber: custom_field hash parsed to json.
Raise CreationError when create fails.
Spec: pass hash keys as strings, not symbols
+Addresses an issue that was causing the tests to fail with oauth gem
Removed unneeded error.json fixture.
Bumped version to 1.5.0