As a user I want to keep a list of my favorite dishes & restaurants

# Tasks

- [x] Add new tables for favorite dishes and locations
- [x] Add models for new tables
- [x] Add methods to Dishes and Locations models to get lists of favorites
- [x] Add a new controller for Favorites
- [x] Change Dishes and Restaurant views to integrate stars for favoriting
- [x] Add a view for listing favorite dishes
- [x] Add a view for listing favorite locations
- [x] Hide favoriting from not logged in stalkers
- [ ] Prettify favorite views (both dishes and locations)
- [ ] Add an icon "currently on offer" to favorite dish view