Rationalize response status code check. Ensure that all bona fide 2xx responses are treated in the same way that "200 OK" is.

Previously, was explicitly checking for response code 200 (ClientResponse.Status.OK).

Now, checks the family of the response to make sure it is successful (Family.SUCCESSFUL). This enables us to POST to resources that return 201 created - without having to handle a checked ApiException.
Merge pull request #101 from joeltgf/master

Change "success" response status code in Java ApiInvoker to all 2xx responses vs. just 200.