Add scrobbling support to watch command

[glensc]

Builds on top of #148

This is mostly proof of concept (but it works!), therefore no readme update.

There's plenty of to optimize:

• skip events, in case laptop suspend/resume there's tons of messages from websocket that should be skipped
• code refactoring, isolate logic to own classes/methods/functions
• optimize on cpu, needs investigating what first
• the code is synchronous, maybe need to rewrite asynchronous
• the sleep(1) maybe is putting too much pressure on cpu
• scrobblng probably needs to emitted only on start/pause/stop, as trakt can itself continue counting play time
• optimize for reducing requests to trakt
• it doesn't start scobbing before play is 1%, this is traktpy implementation problem
• ... that's already a bunch!

NOTE: The Trakt app may need scrobble permission:

• https://trakt.docs.apiary.io/#reference/scrobble