Media foundation video i/o fixes.

Bug in Video for Windows capture init fixed;
Media Foundation based capture finalization fixed;
Highgui tests for video i/o updated.

modules/highgui/src/cap_vfw.cpp

@@ -613,8 +613,10 @@ bool CvVideoWriter_VFW::open( const char* filename, int _fourcc, double _fps, Cv
             close();
             return false;
         }
+        return true;
     }
-    return true;
+    else
+        return false;
 }