Feature listener support

This pull requests adds a new parameter to the easy adapter constructors so now it's possible to pass a generic `Object` to the `ItemViewHolder` through the Adapter. This allows to pass a listener into the `ItemViewHolder` that then can be get and called when an action happens, i.e click on a view. 

The `ItemViewHolder` also providers a method `getListener(Class type)` that casts the listener Object to the desired type and retruns it. 

This new argument is optional so it won't cause any breaking changes.