File cache listdir understands '.' and '..' (fixes #414)

Can't go outside of basedir, though. (Good.)
Woops, remove tempdir after test [ci skip]
fixed Playlist wipe on item removal of first item, closes #418
fixed ui crashing when reordering tracks, closes #412
fixed playlists are always saved as "public", closes #413
fixed albumartfetcher not returning anything when failing, closes #417

it now returns a http redirect to a hardcoded image path, so we don't retransmit this image all the time
Add proper --version switch
Move pid file check behind database setup (fixes #411)
updated changelog for version 0.31.0
Merge branch 'devel' of github.com:devsnd/cherrymusic into devel
Update CHANGES
Release 0.31.0
fixed #417 for the case that albumartfetcher fails, but doesnt crash
Added quickstart, changed setup.py, changed manifest

Added doc to manifest. It would causes errors if it's not there on sdist
creation.
Added quickstart.rst: Is the configuration part of CM.
Changed long description in setup.py pointing to quickstart.rst
Fix README link to Troubleshooting
enabled tag display on client
deployed last changes to playlistmanager
using tinytag to get music metadata instead of loads of other libs
Merge branch 'devel' of github.com:devsnd/cherrymusic into devel
fixed playlist items showing garbage when no metainfo could be fetched