Ant changes to enable Calabash to be deployed to Maven Central

Hi,

These changes enable Calabash to be deployed to Maven Central by running "ant maven-stage".

You'll also need to carry out some additional steps - signing up for an account on the Sonatype server, adding the appropriate Ant libraries, and so on - see the maven-build.txt for details.

If you'd rather not do those steps, let me know and I can deploy Calabash myself to Maven myself, but it would be better if you're able to do it (in particular, I don't have all the JARs at the moment to have a compile-everything work, so I've only tested with "compile").

Let me know if I can help with any of it - I'm by no means a Maven expert, but I've successfully deployed things to Maven Central before.

Inigo