adds create and get method to orm db class
adds list_users method to orm database
Merge pull request #49 from felguerez/delete_listing

Adds 'Delete Listing Use Case'

Great work, Brandon! ^_^
Add AirCycle::CreateReservation Use Case, error validation in CreateReservationSpec.
ORM DB class can now:
  -> create and get listings
  -> create and get reservations
  -> create and get reviews
  -> create and get messages
  -> create and get sessions
  -> get a user by session id
Fixes CreateReservation Use Case spec test to use session_id
Merge branch 'reservation_use_case' into development
Merge branch 'development' of github.com:felguerez/top-secret-final-project into development

Conflicts:
	lib/air_cycle.rb
Merge branch 'ORM-db' into development

Conflicts:
	spec/db/shared_spec.rb
Merge branch 'development' of https://github.com/felguerez/aircycle into create_message

Conflicts:
	spec/db/shared_spec.rb