Fix for files without tag

Closes #6
Added an 'exit' command to the CLI
Added configurable extension whitelist on the scanner

Closes #8
some status messages for scan and flush database more often during scan
to prevent error from cancelling entire scan
fixed indenting with vim pymode plugin, woops (been a while for python)
fixed up transcoding, transcode flac to ogg by default, sped up folder
scan a bit and made artists unique field work properly
okay thats good