User can request on other user's listing.

* Generate Request model
Add maximun guest number to listing
Users can view all requests from and to them.

* Extract request partial
* Extract requests_from_me partial
* Extract requests_to_me partial
User can show, edit and delete a request
Create locations model
Show locations on home page
Make locations index the home page
Install Flutie Gem
Display region show page
Use location select menu when creating listings
Design home page and location show page
Users can view their favorite listings
Likes are under likes#index