Add .msi installer for windows

[brson]

There's an in-progress PR for this rust-lang-deprecated/rust-packaging#2. Requires updated the windows vms.

Nominating because its something I'm working on.

[caizixian]

I think MSI installer is not necessary.

[Nercury]

@caizixian I would disagree - it is very good to have - requires less privileges to install!

[brson]

@caizixian My understanding is that .msi is something of a standard packaging format for windows and should be prefered to other formats.

The above referenced patch has landed but the bots are not building it yet. The VM needs to be updated to carry the needed tools, and I think more review is probably required with an eye toward sxs installation at least.

[brson]

cc @vadimcn @gentoo90

[retep998]

Using .msi also means people would be able to easily install Rust through the command line, which would be very useful for people trying to use continuous integration on Windows.

[brson]

More progress rust-lang-deprecated/rust-packaging#9. Need to install wix on the windows bots and adjust rust-buildbot to pass '--msi' to package-rust next.

[brson]

VMs updated and bots restarted to pass the --msi flag.

[sinistersnare]

MSI installers currently run for windows. should this be closed?

[steveklabnik]

Yes!