added commandline option for an extra lua search path
added commandline option for an extra lua search path

xyliuke/busted,leafo/busted,nehz/busted,mpeterv/busted,o-lim/busted,DorianGray/busted,sobrinho/busted,Olivine-Labs/busted,ryanplusplus/busted,istr/busted,azukiapp/busted