[WF4] WorkflowInstance/App Tests. Early implementation of WorkflowInstance.
[WF4] Early attempt to integrate build system with rest of olive.

-Using common Consts.cs that rest of olive uses. However there is an
issue where it is an old version and updating it to a later version
breaks other parts of the olive build
-Running make on root doesn't make System.Activities
-Can't run tests using make on System.Activities
-Also found stubs for System.Activities.Validation