Add Reservation to Rentr

* Users can create reservation dates
* Users can not create invalid reservation date ranges
* Users can view their reservations for a particular listing
* Users can view all of their reservations
* Users can view all their reservations for a listing if any exist
* Guests can still use app
Blargh. I'd just leave this link here if they're on the reservation page. Changing navigation controls on a webpage is a no-no, and this line is gross.