Refactor express app for NPM use & Express 4 (WIP)

* Expose server/index.coffee as a module
* No longer do NPM Install in grunt
* Attempt to move build steps to prepublish (and their deps to devDeps)
Move packages back to dependencies

So we can continue deploying directly to Heroku. Eventually we'll provide a separate repo/template for Heroku deployments which uses the NPM module, so these deps can be moved back to devDeps.
Nix prepublish for now

:/

Will revisit when we're deploying sites with Buckets _module_ to Heroku, instead of Buckets repo itself.
Change minify task to prepublish for Heroku
Fixes for buckets as an NPM module

* Wrap in an index.js for people without coffeescript
* Nixes the "buckets:" key for config, brings everything up (easier to merge)
* Convert 'buckets' module to simply return app for now (for grunt express, will nix soon I think)
Update procfile command
Update the readme
Merge pull request #57 from davidkaneda/npm-module

NPM module