Added Ember.run wrappers around Leaflet calls.

For Integration testing my app, I added some Test helpers for zooming and clicking the map. I sometimes get following error: `Assertion Failed: You have turned on testing mode, which disabled the run-loop's autorun. ...`. I had a similar issue with Ember.SimpleAuth. It's a problem with external libraries events or interactions, see the [docs](http://emberjs.com/api/classes/Ember.run.html).
Like stated in the docs, I put all setting calls to _layer within an Ember.run.