[krbdev.mit.edu #6038] Add VS 2005 and VS 2008 support for the NSIS installer

[asanka@mit.edu via RT]

The Visual Studio 2005 and 2008 runtime libraries are provided as
redistributable merge modules and a redistributable EXE based installer.
 The attached patch contains source code for installing these runtime
libraries as part of an NSIS based installation by packaging the merge
modules into an MSI that is invoked in the NSIS script.

Using an MSI and the redistributable merge modules instead of the EXE
based runtime installer gives us:

1) Runtime installation for debug builds.  

2) Better cleanup when uninstalling the NSIS based installation.  The
EXE based runtime installer does not uninstall the runtime.

Patch generated against the trunk in directory src/windows/installer/nsis.