Changes to the build system to use grunt-node-webkit-builder.

Makes life quite a bit easier.  Tested on Mac OSX, but not other platforms.  Note that I wasn't sure what you really wanted to call this thing, so feel free to change it :-)

The biggest different is that the grunt task populates build/releases/Glitter for Artemis/<platform>/Glitter for Artemis.  E.g.:

![artemis-build](https://cloud.githubusercontent.com/assets/143317/3363442/67b3ffe6-fb13-11e3-844e-71a55cb048e0.png)
Is there any way to still do this via Grunt? I'd prefer not to manually zip all files for each architecture and change the filename to include glitter's version.