Upgrade to CBM 2.0

Hi Tim,

I performed the necessary modifications needed to get Gemini to work with Caliburn Micro 2.0.

This mainly involved 

1) Replace the Nuget package for CBM
2) replacing calls to `ActionExecutionContext` to `CoRoutineExecutionContext`
3) Adapt to the new situation in the bootstrapper where the executing assembly is not returned standard (and Gemini needs this).

In all, changes seem relatively minor. Everything works just fine after applying them.