Switch Buildsystem to Gradle

gradle provides a bunch of benefits over ant build scripts

1) automatic dependency management (no jars in the repo)
2) easily expandable (adding, say, a test suite or easy building of a distributable jar)
3) importable into eclipse and idea for those of us who use IDEs

the change is a little intense, I will admit, but this is ultimately easier to manage, in my mind.  things like images and font files don't live inside of packages, instead being split out to a resources folder.  Test cases live in their own source tree and don't have to be excluded.