Updated local cpath

torch-pkg installs library files to <local-instal-prefix>/lib/torch/lua
(changed in c622014a5d25668f2308277d68fc9b1de5b2d0d2 and
e500d7cea89b2454b1219c3a883a0cae2f6cc9fe). torch-env now adds this
location to the cpath, whereas before it only added
<local-install-prefix>/lib/torch which was the correct location prior to
c622014a5d25668f2308277d68fc9b1de5b2d0d2.