Replacing maven with gradle

THIS ISN'T READY TO BE MERGED YET.

The gradle config is a lot more manageable than the Maven config. Gradle can also replace the current Rake-based packaging process.

This is mostly @crasu's work on #60, with a few additions.

TODOs:

 *  Figure out how to create a releasable ZIP from the gradle build
 *  Add the teradata subproject so it at least builds