Add happy path test for records_owner feature
Add Owner model; passes all unit tests
Record owner happy path test passing
Record owner missing attribute test passing
User story records_owner is complete
Add happy path spec for associates_building_with_owner
Add association to Building model
Associates_owner_with_buildling passes happy path test
User story 3 (associates_building_with_owner) complete - passing all tests

- Specs:  Added spec for dependent: :nullify relationship, modified
other specs to fix issues caused by FactoryGirl

- Database:  Added owner_id to Buildings table

- BuildingsController: Permit owner_id in strong_params; pass buildings
to index method to allow displaying all buildings in index view

- OwnersController:  Added index (need to view all owners to choose
which to delete) & destroy methods

- Building model:  removed validator for owner (should be optional
field)

- Owner model:  Added association with buildings

- Routes:  Added index & destroy methods for owners

- Views:  Added index view for Owners, inserted table of buildings in
Buildings index view
Add headers and links to views; modify Owners table in index view