Added the start of java support.

Java compilation and jar creation are supported.

Squashed commit of the following:

commit 502ca3541bc7a7b088f379f44d12a29f3659baf2
Author: Avinash Baliga <fifoforlifo@gmail.com>
Date:   Tue Apr 30 22:48:44 2013 -0500

    Added jar creation.

    Jar files added to javac classpath are also
    now treated as dependencies.

commit 93b773386ee460e0aae0e49b78d95e7c4b970fd4
Author: Avinash Baliga <fifoforlifo@gmail.com>
Date:   Tue Apr 30 00:10:57 2013 -0500

    Added basic java compilation support.

    Added task, project, toolchain for Oracle/Sun javac.
    It crudely handles dependency tracking too.