Vetoed track should be forgotten

If a song is vetoed + skipped (exceeds maximum vetoes), it should be
forgotten so it's no longer eligible for auto-play
Adding config key for ForgetTrackThatExceedsMaxVetoes

Functionality controlled via the last commit for "Vetoed track should be
forgotten" must be controlled by a config key.
Merge branch 'master' of https://github.com/wdthem/PlayMe into wdthem-master

Conflicts:
	PlayMe.Server/ISettings.cs
Updated web service reference with new signature for ForgetTrack
Merge branch 'wdthem-master'