remove grunt, use testem and broccoli, build ember-inflector from bower

This will need to be extracted to some sort of ember-cli blueprint. I'll be working on that.

cc @rwjblue
I think this might need to be `ember build --environment production`.  Currently, this is using `BROCCOLI_ENV` to determine if minified output should be put into `dist`.  If you make the change to `--environment` you'll need to check `process.env.EMBER_ENV` which is what gets set by that `--environment` flag.