Headless Server config through command line

This PR adds support for three cmd line params in the PC facade.

The log file of a test run can be found here:
http://jenkins.movingblocks.net/view/All/job/RunTerasologyServer/15/console

A few notes:
* Module jars seem to be discovered properly in the "modules" subfolder, but their content is not available in-game.
* Maybe we should consider moving the headless server code to a separate facade in the long run?

Fixes #1051