Refactored refresh token

[manveerxyz]

I moved the whole refresh functionality to spotify_tools.py as it seemed like a better option versus having spotdl.py meddle with spotify_tools.spotify

EDIT: Solves Issue #237

[manveerxyz]

Also, can someone try testing the refresh functionality on their machine, I keep getting:

'Spotify' object has no attribute 'get_cached_token'

Even though their documentation clearly has the function.

[ritiek]

Ah crud, my bad. The methods get_cached_token and refresh_access_token are available only on spotipy.oauth2.SpotifyOAuth class and not on spotipy.oauth2.SpotifyClientCredentials class. Since, we don't need access to personal information of our token user, it doesn't make much sense to use spotipy.oauth2.SpotifyOAuth class for authorizing ourselves as it further requires verification of redirect url.

Let's keep the way it currently generates new token.

However, I like the idea of creating a new function in spotify_tools.py and be done with just calling something like spotify_tools.refresh_token() which overrides the previous spotify instance in spotify_tools.py. I'd accept this PR if you could just make this changes. :)

[ritiek]

Merging this in. Thanks!