Refactoring CanCan abilities

* Adding thorough unit tests for site admin abilities on trip_tickets and trip_claims
* Adding thorough unit tests for site admin abilities on users
* Adding thorough unit tests for site_admin abilities on providers
* Adding thorough unit tests for site_admin abilities on provider relationships
* Adding thorough unit tests for site_admin abilities on services
* refining test data
* Updating ProviderRelationship class methods `relationship_exists?`, `partners_for_provider`, and `partner_ids_for_provider` to take into account whether a relationship is approved or not
* Adding thorough unit tests for provider_admins abilities on trip tickets
* Adding thorough unit tests for provider_admins abilities on trip claims
* Adding thorough unit tests for provider_admins abilities on users
* Adding thorough unit tests for provider_admins abilities on providers
* Adding thorough unit tests for provider_admins abilities on provider relationships and services
* Adding thorough unit tests for schedulers
* Removing legacy tests
* Verifying permissions in UI and adjusting as necessary
* Fixing some test files
Merge branch 'ability-refactoring'

Conflicts:
	test/integration/admin/admin_user_test.rb