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
Merge commit 'c2f68f624db36708a954424f2a154ea3c91d0f4b' into feature/implemented-negation-bucket-search

* commit 'c2f68f624db36708a954424f2a154ea3c91d0f4b':
  Update the readme
  Update procfile command
  Fixes for buckets as an NPM module
  Change minify task to prepublish for Heroku
  Nix prepublish for now
  Move packages back to dependencies
  Refactor express app for NPM use & Express 4 (WIP)