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.