Add bower.json, to enable bower install maphilight

After merge, run:

    bower register maphilight git@github.com:kemayo/maphilight.git

---

I believe the `1.3` tag need to be changed to `1.3.0` before it can work with bower, so I specified `1.2.2` until then.
https://github.com/bower/bower#registering-packages