Expandable should provide a header element

[Nekhelesh Ramananthan]

While using Expandables in my app, I noticed that I had to repeatedly define the following code http://paste.ubuntu.com/7108917/ to just create a header text. On discussing this with Mzanetti on IRC, he agreed that an Expandable should provide a generic Header element where the app developer can add anything to the header.

So for instance for adding a text in the header, it would be simple as,

Expandable {
    header: {
          Label {
              text: "header text"
         }
   }
}