bower works fine when installed locally

A starter kit is more welcoming to new users when it minimizes the
work they have to do just to get started. There's little reason
to install bower globally, and then call it separately, just to
use this starter kit. This change automatically installs bower
locally, and then runs `bower install`, so the user needs never
call bower directly. (I can provide a similar modification to
obviate a global grunt install; just let me know.)