Build Raphael as a compatible anonymous module for AMD using Grunt

I've incorporated seriema's pull (maintaining his authorship) into this pull request so it can all be one merge. The build task constructs raphael.js in a way that makes it a compatible anonymous AMD module (by treating the separate SVG and VML files as part of the main Raphael source rather than separate dependencies). This will give AMD users a much easier time including Raphael.

Note: This does not affect the global definition codepath and Raphael is still defined globally even when included with AMD (for convenience and for libraries/plugins that depend on Raphael to be there globally).