Currently in 6u20, each person that wants to build the install ws has to do an extra step in setting up the ALT_AUMSI_CAB property to point to the latest au version. This is a hassle for most groups that don't care about this, and confusing to those who don't know which version of AU they should be using.

Instead, we should bundle up the proper version of au msi/cab into the install ws. It's small enough in size that it shouldn't have an impact on bloating the ws. We'll still offer the ability to override with the ALT_AUMSI_DIR property.