Ember Add-on now depends on bower instead of using pre-built dist

Long story why...Ask me or @rwjblue sometime and we'll talk your ear off for an hour......
Can you add the `bower install` into the `prepublish`? 

prepublish is ran when running `npm install` (without a package name argument), and before publishing to npm.  Adding `prepublish` as `bower install` will still leave the instructions in the README on how to build this project work (basically just `git clone && npm install && npm start`).