Support version updates

[synhershko]

I installed the platform using the PI, then downloaded the latest vsix from the build server and running it I got "this is already installed"

Had to go to VS, remove SM, and install using the vsix

We need to make sure the update process will work when going forward

@indualagarsamy @andreasohlund @SimonCropp

[andreasohlund]

The reason is that the choco package is still left in c:/chocolatey/lib

I don't think this will be an issue when we go past beta since each version we put out will have a unique version number. cc @SimonCropp

[andreasohlund]

And give the fact that we'll make the PI smarter about detecting new versions I think the only ones effected is ourself when testing.

[johnsimons]

IMO the proper fix is to not deploy this via PI and use VS "Extensions".

[indualagarsamy]

moved to Particular/PlatformInstaller#160