2550 datahub user types

Hi @rossjones 

here's the work on user types: http://trac.ckan.org/ticket/2550

It requires the master branch of ckan.

The readme describes how to run the tests, and what the available paster commands are.  Further, I've modified the user_update and user_create actions to allow a user's payment plan to be set.  So you can check those out through the action api.