Enable config files for openrail

This patch adds code to read the configuration from
/etc/openrail/openrail.cfg.

By moving to this method, it means the code can be
packaged into a .deb or other distibution format
and configured using a configuration management
tool such as puppet or chef.
Merge branch 'feature/add_config_file' of github.com:proffalken/openrail into feature/add_config_file

Conflicts:
	corpusdb.c
	include/libopenrailconfig.h