Proposed solution to issue #527 - Makefile install target for Unix systems

The additional bash script is there to circumvent the hardcoded pathing of cataclysm binary to the same directory for 'data'.
It probably could be solved better, like adding 'data' to the $PATH temporarly.
I've opted against throwing the whole thing into /usr/bin - seems like a bad idea.
Overall it should be easy to customize for packaging.
Comments and improvements welcome!