Pagination added for contact endpoint.
Introduced PagedContext and query message for contacts that returns
the required contacts together with the number of all contacts in db.
Refactor phonebook's models to merge both implementation. One model
class is used for both main and search results windows.
Improve search by matching entered string against:
- first_name " " last_name
- last_name " " fist_name
Sort results by last_name " " first_name, favs first.
Small improvement to the list view has been added to deal with
asynchronous db reads.
Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>