Merge branch 'release/0.4.3' into develop
Basic song streaming with tornado httpserver
Added CherryPy
rebuilt streaming server in CherryPy
Added 'proxy_tracks' option, proxy URLs are now returned directly from inside track objects.
Minor update to logging in 'spotify2.server'
Removed 'spotify_web'
Moved 'spotify2' library to 'plugin'
Added 'spotify.py', 'concurrent.futures', 'requests_futures' and 'pyemitter' libraries
Updated to work with spotify.py (authentication working)
Updated spotify.py
General fixes/changes for spotify.py, working playlists view (with playlist folders now)

 - Basic playlists view on spotify.py
 - Real support for playlist folders
 - Restructured views (async routes)
 - Updated @authenticated decorator
Updated spotify.py
Updated PyEmitter
Playlists now show their real name (instead of URI)
Updated spotify.py
Playlists now show tracks with full metadata
Updated spotify.py
Searching mostly working again (no official playlist images yet)
Updated spotify.py