Implement simple command filtering
Implement simple command filtering

This patch introduces both filtering mechanism and
a simple service that can be used to control this mechanism.

eburkitt/majordomo,ajanicij/majordomo,zeromq/majordomo,eburkitt/majordomo,zeromq/majordomo,eburkitt/majordomo,eburkitt/majordomo,eburkitt/majordomo,ajanicij/majordomo,ajanicij/majordomo,zeromq/majordomo,zeromq/majordomo,zeromq/majordomo,ajanicij/majordomo,ajanicij/majordomo,ajanicij/majordomo,eburkitt/majordomo,ajanicij/majordomo,zeromq/majordomo