Remove SSH.NET dependency since it can't be used in projects with strong names
Give the SDK and testing assemblies strong names

* The SDK key is stored outside the Git directory structure and must be provided by individual developers
* The testing key is for development only and included in the repository (per-user keys would require each developer use a different set of [InternalsVisibleTo(...)] attributes)
Merge pull request #228 from sharwell/StrongNames

Strong names