Engine: Adding customized Taxonomix to handle the case of associating
one organization per entity - in this case Providers.
Engine: Removing the thread session from the User model.
Engine: Removing Pulp user login field from being loaded.
Engine: Addressing comments and moving taxonomix to concerns folder.
Merge pull request #2712 from ehelms/enginify

Engine: Adding customized Taxonomix to handle the case of associating