tear down completly, needed if more layers are defined with different…

… zcml files

src/z3c/testing/layer.py

@@ -87,6 +87,7 @@ def tearDown(self):
         fsetup.base_storage.close()
         fsetup.base_storage = self.original
         fsetup.tearDown()
+        fsetup.tearDownCompletely()
 
 def defineLayer(name, zcml=None, appSetUp=None, clean=False):
     """Helper function for defining layers.