adding option for installing Open MUL Controller

please add to the main branch
This wouldnt work. cargs are the arguments for your controller. if you give not arguments right now, it currently defaults to packetdump as the default argument. so the command run would be mul -P packetdump, which makes no sense because 1) packetdump is a NOX controller module and 2) the -P option is for port, not a module name. mull2sw is the application you are trying to run with MUL, not packetdump. You should also be able to do this without modifying Controller.