doubleClickZoom opt-out and support for custom event callbacks

Hi,

I cleaned the repo and kept it up with the developement:

since https://github.com/tombatossals/angular-leaflet-directive/pull/76#issuecomment-20927742,

i added support for custom events callback defined in the parent scope, user can set callbacks for each event supported in the leaflet:

reference: http://leafletjs.com/reference.html#map-click