Completed transition of package to the new torch7 environment

There were a couple of "torch-lua" calls which I've changed to "th", the "torch-env" package was removed, so I changed that to "env". On Ubuntu 12.04 64bit, calls to sys.execute("some bash code & echo $!") do not return the PID in a string, but sys.fexecute does. I've changed all calls of "sys.execute" to "sys.fexecute", since the latter is more robust. Examples now work with both "th" and "qth".

Thanks for a handy package!