Added Search Location button

Hello,
I added a "Search location" input to easily locate an address on the map.
It uses the Google Maps API's GeocodeRequest object which returns the LatLng, than sets the marker's position and centers the map.
![google-maps-add-on](https://cloud.githubusercontent.com/assets/7031651/4178678/1870665c-36a2-11e4-89c5-dab991da25a8.jpg)