[WF4] Fix-up for olive build integration.

-Changed directory name for tests in line with build system expectations
-Changed namespace of tests
-Added missing TestFixture attributes, (XS ran the tests regardless)
-Removed nunit features not supported by the older version in use in olive
  -Commented out Timout attributes in tests (could lead to test hangs when
   regressions occur)
  -No longer using Assert.IsEmpty (ICollection)
[Olive] Fix-up of issues on monkey wrench

-changed MONO_PATH to lib/mono/4.0 so nunit can run under .net 4
-signing Microsoft.Web.Atlas was failing, disabled signing it for now
-added missing WF4 test to test sources
-fixed a failing test for WWF3