Adds a search view and a test for it
Changed display of some boolean fields in detail template
Adds a list of received trade requests on user's index page
Adds a preview view for one's own listing
Several additions:
	* A send_trade_request view.
	* The detail view will display if the viewed listing has sent
	a trade request to the viewing listing, or vice versa
	* Changed template inheritance so that any messages sent
	via Django's built-in messaging will be displayed on any page
Adds ability to perform search function with empty text field
Adds a public search form to the start page.

Former start page for logged in users is moved to /dashboard/
Adds new user model to admin site