Versioning scheme

[sayedihashimi]

If this becomes the command line for creating projects in dotnet cli then we need a versioning scheme to ensure that templates can still work with new releases of dotnet.

[mlorbetske]

We'll need to burn in the CLI version when generating the project.json files that restore the templates

[mlorbetske]

What's the right way to do this? Do our templates/engines just need to be forward compatible with SxS installations (no work required)? This might be related to #49, #50 and #51 where we update the assemblies that generate the content - we'll need to make sure somehow that the generators/sources don't try to slide ahead of the CLI version - but we need to know how to do that. /cc @sayedihashimi

[mlorbetske]

We should allow passing constraints through from the broker (or however the orchestration for update/install turns out) to the NuGet integration that'll be done in #60