Add ice-cube gem.
Add Booking model.
Add empty BookingHelper.
Add Booking routes.
Add Bookings controller.
Overhaul factories to use sequencing and associations.
Set up Booking association with 'room' and 'user'.
Use shallow nested routes for bookings
Amend sede file to include bookings.
Adjust indentation.
BookingMethods added.
Add extra validations to Booking model.
Amend Booking factory to comply with new validations.
Remove user_id from white-listed attributes for bookings.

* user is set to the current_user when booking is created
* user cannot be edited.
Bookings belong to 'bookers' (pseudonym for users).

Previously, bookings belonged to users.
Fix broken seed file.

(Was not passing validations for bookings)
Boot-strapify Booking views.
Add drop down selectors to booking form.
Add Reservation pseudo model.
Add calendar model.

* A room has a calendar
* Room calendars are created when their room is created
* Calendars are not exposed as resources
* Rooms accept nested attributes for calendars
* Calendars have many bookings
* Specs amended accordingly
* Views amended accordingly