Feature: addMarker() now supports custom icons

Hi there,

I started using your leaflet wrapper and found that I wanted to override the default marker that is created by the addMarker() call. Leaflet already supports this, so I made a minor change to bindings.js to parse out the "icon" option and turn it into an L.Icon.

I'm not a Javascript programmer, but I took a shot at this and it seems to work fine for me.

Cheers,
Chris