Markers are now able to call a click function of the controller and $markerModel will be injected

This is an attempt to fix #288.

normally i would want to specify a clickable marker-collection like this:

<markers models="models" click="clickModel($markerModel)">

However due to the & scope binding of click you can't specify a function. & will evaluate and thus return the result of the function :S it could however return a function (and act as a factory more or less) but i am not sure if this is really a good fix..

What is possible now:

<markers models="models" click="clickModel">

The & binding will resolve clickModel to the function itself. The function will then be called with $markerModel as an argument.

I am not sure what a good fix would really look like. Changing the & might break backwards compatibility.