Handle versions of Roslyn greater than v1.0

[duncanp-lseg]

Currently the SDK is built against Roslyn 1.0. This means that it if it is run against analyzer packages that use a newer version of Roslyn, it will not find any analysis rules (the SDK will be looking for classes that inherit from DiagnosticAnalyzer v1.0, but the analysis rules will be inheriting from e.g. v2.0).

This will not affect the version of Roslyn that is required to execute the rules during analysis, only the version of Roslyn that must be available when running the SDK.

Options to consider

1. binding redirect, relying on backwards compatibility (if it works, this would maximise the versions of MSBuild/Roslyn the SDK can work with)
2. change the version of the NuGet package used by the SDK