Restore lost functionality to the arrivals fragment

Summary:

• Use better logic to search for arrival times using MaTO

• Fix showing logic for palina in arrivals

• Remove "App" with Muoversi a Torino in lower message

• Improve toast messages adding the fetcher prefix

• Clear arrivals when launching new request

Test Plan:
Search "1254". Opened. See arrivals of MATO. Open in map: it works. Back. It works.

Change arrivals source to GTT: it works.

Reviewers: valerio.bozzolan

Reviewed By: valerio.bozzolan

Subscribers: valerio.bozzolan, Libre BusTO

Project Tags: Libre BusTO

Differential Revision: https://gitpull.it/D223