Polish the UI

[MichalGoly]

At least:

1. Centre the text in the views of the RecyclerView
2. Prevent track's title spanning on multiple rows in the PlayerFragment. Probably by limiting the length of the track being displayed to a fixed value, maybe based on the resolution of the screen?
3. Handle multiple tracks' covers sizes
4. Add ripple effects to the Player's buttons

[MichalGoly]

5. Add a top border to the BottomNavigationMenu