Update api.py

Logic error exists in set_password.  Should be using and, nor or.  The normal response here is a 204 (it worked), and or will fail fast when the first condition evaluates to true.
Update api.py

_call_salesforce currently uses a hardcoded set of headers that is not callable.  Passing in the Salesforce object's headers allows them to be updated after creating the object, which means we can pass SForce-Auto-Assign and other headers into API requests.
Merge pull request #45 from AllClearID/master

Minor updates to correct bugs