Update ISSViewPrototype.m

If xml tags (labels) containing properties are embedded in another view - createViewObjectFromPrototype can not setViewObjectPropertyValue in the implementation.

           <PrototypeExampleCell prototype="prototypeExampleCell" class="prototypeExampleCell">
                <view class="group">
                     <label property="label1" class="prototypeExampleCellLabel1"/>
                     <label property="label2" class="prototypeExampleCellLabel2"/>
                </view>
                <label property="label3" class="prototypeExampleCellLabel3"/>
                
                <!-- Example of how you can directly set the backgroundView and selectedBackgroundView properties of a UITableViewCell: -->
                <view property="backgroundView" class="cellBackgroundView" add="NO"/>
                <view property="selectedBackgroundView" class="cellBackgroundViewSelected" add="NO"/>
            </PrototypeExampleCell>