Asset management

First stab at this, coming from #292.

Moved stuff from the `public` folder into `assets`. There's a `packages.json` file in there that tells geddy how to package together the assets. I just use the file extension to decide how to deal with files.

If a file in the assets directory is not used as part of a package, it's copied over to the public folder (e.g. images).

Added a jake task `jake assets` that will compile the assets using `lib/assetcompiler.js`. Also added a bunch of dependencies to the stock `package.json`.

Stuff I'm unsure about:
 * Are we going to watch files?
 * Should this be a jake task or part of the geddy cli?

Stuff that still needs to be done
 * Minification should only happen in production mode
 * Assets should be placed into a folder with a hash of some sort. Need to think of a fast way to do this without recompiling everything (takes a couple secs, annoying).
 * Probably shouldn't use `console.log()`...
 * Tests

Let me know what you guys think.