updates to be able to use auth library with other appc libraries

Added some improvements to allow this common auth library to be usable by node-acs.

- added standard auth codes as part of exceptions used by node-acs (and good practice)
- added additional meta data from login result to be able to be used (such as firstname, etc)
- added additional unit tests for auth login
- fixed unit test failures by specifying older should version. newer should.js library doesn't support same syntax as we are using