Small fixes

Update for recent spotipy changes.

Fix embedded cover art

• Download images using urllib.

Fix playlist and cover art download

• Fix playlist and cover art download.
• Add documentation on how to set Spotipy variables in the configuration file.

Hardcode cache/settings directory

• Hardcode cache/settings directory to ~/.spotify-ripper.
• Small output tweaks.

Program output and media formats update

• Reformat all code.
• Remove Python 2 support.
• Simplify Readme.
• Fix some optional media formats for output and update dependencies.
• Adjust program output:
  • Print separator only between each file
  • Print in bold the action (rip, skip, etc.)
  • Always print [ index/total ] when ripping multiple tracks, even for skipped ones
  • Be more concise for file information and use a list for all items
  • Do not print debug statements (loading, getting, etc.)

Fork cleanup

• Clean up project (remove unused files, obsolete references, README, etc.).
• Small Python updates & cleanups.
• Improve playlist ripping:
  • Do not remove tracks by default
  • Improve help output
  • Do not print that we are getting data from the spotipy api at every call
  • Update README with instructions on how to get the spotipy required IDs