Fix #17 - Convert handler when used in prop value

Fixes the conversion of "handler", when used in array,
passed as property value. Example:

new A.Toolbar(
    {
        children: [
            {
                handler: function(event) {
                    instance._editEntry(contact);
                },
                icon: 'edit',
                label: 'label'
            }
        ]
    }
).render();