add one ip to blacklist
	renamed:    src/cache2.c -> src/cache.c
	renamed:    src/dnsproxy_ldns.c -> src/dnsproxy.c
	deleted:    src/dnsutil.c
change source file name
add license infomation
remove the funcitons that not used
	deleted:    src/dns.h
add license infomation

process listen_ip, listen_port options
remove some function definitions that not used