Allow arbitrary tag setting, clean up .pyc's

Let us set arbitrary options using /etc/sysconfig/tcollector, primarily for adding extra tags (eg; TCOLLECTOR_FIELDS="-t tagk1=tagv1 -t tagk2=tagv2").
Defaults to adding the host= tag if TCOLLECTOR_FIELDS isn't defined (to maintain backward compatibility).

Also removes *.pyc files on startup - sometimes upgrades aren't getting picked up because the *.pyc's are often newer than .py's shipped in .rpms etc.