FINALLY displays item availability in the show view in a beautiful js calendar
Allows user to book a listing with specific datesOrderItem connects to availabilities to display quantity.
Scopes unreserved orders so that the item show calendar displays only available dates
Merge branch 'availability-part2' of github.com:MarcGarreau/the_pivot into lolomg

Conflicts:
	app/models/item.rb
	app/views/items/show.html.haml