[krbdev.mit.edu #7390] WiX variable expansion uses deprecated character

[Benjamin Kaduk via RT]

[kaduk at MIT.EDU - Fri Sep 28 17:06:06 2012]:

> when building the installer, we get lots of warnings that we're using
> '$' instead of '!' to expand
> variables, which is no longer recommended.  We should update our
> behavior.


Commit abeed0da177a5c58eb3fa0a72e473fed294ae884 mentions this bug.