Modified RefrershHandler tag handler to read its attributes as value expression if defined so.

Although the interval can now be set via EL, the refresh rate itself is not changing as expected. Here is what I am seeing:

1. Default interval set to 5 seconds. Clicking the commandButton changes the interval to 1 second which works expected as the refresh rate speeds up. However, you cannot revert back to the 5 second refresh rate.

2. Default interval set to 1 second. Clicking the commandButton to change the interval to 5 seconds does not alter the refresh rate.

Test case attached.

There were two problems that created this issue:

• The RefreshSetupOutput.encodeBegin was not marking the root element as being a onElementUpdate user. Because of this the ice.onElementUpdate callback in the client responsible for terminating the refresh thread was not invoked when the refresh interval was changed. The result was that both the 1 second and 5 seconds refresh thread were running after clicking on the "Toggle Interval" button.

• The RefreshSetupOutput.encodeEnd method was not overriden with no-op method causing the UIOutput to render and additional 'span' end tag. The correction mechanism in our DOMResponseWriter would just add the 'span' element. This resulted in having to 'span' element with the same ID in the document thus confusing the onElementUpdate feature.

Changed RefreshSetupOutput.encodeBegin to mark the root element as onElementUpdate enabled so that server-side onElementUpdate implementation works properly. Also, overriden RefreshSetupOutput.encodeEnd with empty body method so that a 'span' end tag is not rendered by the inherited UIOuput component.