Provide Nuget package for easier deployment

[csoltenborn]

Add NuGet support such as that of the xUnit or nUnit test adapters.

[csoltenborn]

Committed first working version. Package is generated by post build event of VsPackage project and ends up in folder VsPackage\bin. Package can be tested by using a local NuGet feed. For C++ projects having that NuGet dependency, discovery and execution works out of the box (even without restarting VS). However, only user settings do apply with this approach - no actual vsix extension is installed, no options or toolbar are available.

Alternatives:

• We might be better by roughly following the recommendation in the last comment of this blog entry, i.e., make VS recognize our VS extension (as unpacked by NuGet in the solution's package folder) by performing registry modifications during NuGet installation of our package. See also this blog entry.
• Another approach could be to pack the vsix as is and launch it during NuGet package installation. This is discussed here and here.
• Finally, we could just do the installation process ourselves (see this blog entry).

[csoltenborn]

Installation with NuGet will only provide basic functionality (test discovery and execution, solution and user settings), but no options or toolbar will be available.