propertyIsModel attribute added for em-select

[jackmatt2]

73 #72

new attribute for {{em-select}}

• propertyIsModel : will bind to the model in the collection instead of the value.

            {{em-select
            label="Employee"
            property="employee"
            propertyIsModel=true
            content=employees
            optionValuePath="content.id"
            optionLabelPath="content.name"
            disabled=false
            prompt="Please Select"
            }}

Now the employee object will bind to the actual employee model not the id.

[pedrokiefer]

This patch works fine, solved my issue with selecting multiple values. I think it should be merged.

[asaf]

Pushed.