There has been some confusion over which type of Wix3.5 installer we should be using. There is a Wix3.5.msi installer and a Wix3.5 zip installer. They both have different directory structure. The MSI drops the exe's into a bin subdir, where the zip puts it in the top directory. We are currently using a zipp'ed up image of the msi installation, which is not the right way to do things.

The correct way is to use either the MSI or zip as they are shipped by Wix team. We have chosen to use the zip, as it's easier to install.

As part of this change, we will also add an additional sanity check to make sure candle.exe binary actually exists in the WIXDIR. We will move the default wix installdir to c:\devtools\wix3.5, to make the transition easier for the next few builds.