Small addition to the Excel Services AJAX library

Hi,

I am doing some work on a new sample (called EwaCompanion, more on that soon).

As part of that work, I had to add a few things to the AJAX library and fix a few issues.

The main addition is the support for the .refreshAll() method  which will execute the Excel Services Refresh Web method with an empty parameter (causing everything to refresh). I also fixed a few bugs (for example, .calculateWorkbook did not work...).

Enjoy.