title: Binding sap.m.RadioButton
body: <p>how do I bind the selected property of <code>sap.m.RadioButtons</code>? I understood that I group them with the <code>groupName</code> property but I'm totally missing sth. like <code>RadioButtonGroup</code> to get the selected key or alike. <code>sap.m.RadioButton</code> does not even provide a key? Could someone give an example?</p>
  
  <pre><code>&lt;RadioButton groupName="MyGroup" text="Option A" selected="true" /&gt;
  &lt;RadioButton groupName="MyGroup" text="Option B" /&gt;
  </code></pre>
  
  <p>Say my model looks like this: </p>
  
  <pre><code>{ currentOption: "A" }
  { options : [ { "name" : "A" }, { "name" : "B" } ] }
  </code></pre>
  
  <p>The alternative option would be "B". How to map this?</p>
  
  <p>BR
  Chris</p>