Support for user favorites

[tdipisa]

Introducing Favorite Resources for users with filtering/search support. Favorites should be provided via a new entity on the DB side with related services (cardinality is between User and Resource table as 1-N).

The /extjs/search/list and /extjs/resource/{id} response payloads (see #379 and #380) should include a boolean property indicating if a resource is favorite for the requesting user.

All users should be able to perform this requests independently on their role.