Feature/panning options

Needed the option to disable panning for a project I'm working on, figured I'd submit the changes here as well, since not all of the leaflet map options are passed to the leaflet directive.

I did not add a test for these two options as it does not look like the current tests check for some of the other similar options.

Also looks like it would be relatively trivial to support all of the Leaflet map options:
http://leafletjs.com/reference.html#map-options
I can't do it now, but if you'd like I'd happily look into doing so, maybe once you've released your split files branch?