low compatibility with luarocks install

[fredowski]

Hi,

your code is used in an example for the machine learning environment torch. However, your installation method expects lua5.1 in a default place and the pkg-config to be there. Therefore there have been some tweaks introduced to install this package.

kuz/DeepMind-Atari-Deep-Q-Learner@8466031

The standard torch installation installs lua or luajit in some local directory and depends on luarocks to install dependencies. I think the rockspec plus Makefile could be modified to have an easier install via luarocks.