- Added model and ran migration for pimAdmins

- Migrated database to add pimAdmin_id column to posts
- Created has_many / belongs_to relationship between pimAdmins and posts.
- Directly added (bad!) a testUser to pimAdmins and associated all existing posts to it.
- Changed references to posts.name field in _form html (CU - no longer assignable via form), show (R) and index (R) to reflect association with pimAdmin and display pimAdmin.username
- Migrated development database to remove the no longer user post.name column.
Next: generate pimAdmin controller, CRUD, remove hacked in user-testuser