Add dependency version for framework profiles

This allows the nuspecs to use framework profiles which may also contain multiple Nancy dependencies. An example of why can be seen here [nancy.viewengines.razor.nuspec#L15-24](https://github.com/NancyFx/Nancy/blob/79a1eec5d8e94c5d428d99e04bbe642746d906a6/src/Nancy.ViewEngines.Razor/nancy.viewengines.razor.nuspec#L15-24)

Fixes #1634