Fixed bugs in original module, added domain user support.

Runas that allows quoted arguments, chained commands, commands with arguments, running with domain accounts, and does not require any privileges to run.  Also correctly handles cases where cmdout is set to true, but the command returns no output (original version throws a nasty error).  Original version also does not work unless you
initiate the module from SYSTEM (even though it claims to be able to run as an administrator).