Rename README to a markdown file
Clean up the pom.xml, upgrading JUnit and maven-compiler-plugin
Whitespace cleanup
Upgrade to the latest JNA which has better support for FreeBSD
Add a FreeBSDCLibrary class to support slight API changes between FreeBSD and other BSD-like OSes

This fixes JENKINS-21507, and could probably be cleaner, but I get the
impression that this code isn't very well kept Java anyways