Framework downgrade (4.5 -> 4.0) (...)

- NUnit package upgrade
Merge branch 'f-discoverer-spi' into f-yodii-lab
First hit in the ConfigurationSolver (one of many to come) Additional details below:

- The FinalConfiguration (used to access the items status value) is now a parameter of the ConfigurationSolver.
- The ConfigurationSolver class handles the static resolution while the DynamicSolver takes care of the dynamic component (with the YodiiCommands).
- The PluginData/ServiceData classes hold processes that should be divided into 3 distinct types (structural, config, dynamic).
- PlanCalculator and strategy classes/related methods have been removed or need to be updated.

Many, many more changes to come
Update of the ConfigurationSolver, builds successfully
Merge remote-tracking branch 'origin/f-discoverer-spi' into f-yodii-lab
Yodii.Lab: Added tests. Builds. (...)

- Fixed move to 4.0.
- Now using AsReadOnlyList() from CK.Core.
- Added WIP Yodii.Lab tests (not building yet).