VS: Add Resx configuration to the vcxproj file

In my project group we are using CMake to generate c++/cli winform
projects and I noticed the work done in commit 79ec7868 (VS: Add Windows
Forms Support, 2013-04-29) was in the right direction for solving some
of the problems we were facing.

The changes as submitted was breaking some functionality in our
projects, so I made some changes that fixes our problems and I believe
that it will also work for others.

* Resx files did not link correctly with the winform h-file so I added
  the Resx configuration to the vcxproj file.

* I removed the functionality for setting <CLRSupport> true for the
  project based on if an resx-file is pressent.  This is preventing
  us from using native cpp code.  Also this do not address that some
  projects will need to set other options like clr:pure, clr:safe.
  This could be implemented as a cmake option, so it is possible to
  specify exactly what is needed.  Existing VSWindowsFormsResx Test
  project is updated so it will be working with my changes.
Merge topic 'vs-windows-forms' into next

6c9712c VS: Add Resx configuration to the vcxproj file