Added descriptions, email and phone to seller locations

This enables vendors to set specific contact details for each location.
This change also required changes to be made to the way authentication
works so that we can obtain the users’ email form Facebook to use.

Note: Accessing email and other extra fields from Facebook requires
permissions to be set on the *client* side. (NOT the server). This is
done by setting the “scope” parameter on the OAuth.popup function in
navbar.js. Once these extra parameters have been added, users must
approve beLocal access to them on Facebook. Then they can be accessed
either client or server side without any hitches.