Geolocation control with Leaflet.

Hi there,

As mentioned by me in the [forums](http://forums.webhook.com/t/roadmap-future-plans/240/6), I created a geolocation field with [leafletjs](http://leafletjs.com/). 
You can enter both an google url like

```
https://www.google.nl/maps/place/London,+UK/@51.5286416,-0.1015987,11z/data=!3m1!4b1!4m2!3m1!1s0x47d8a00baf21de75:0x52963a5addd52a99
``` 

and a location string like

```
51.5286416,-0.1015987
```

Hopefully you'll like the idea :)