Small cleanup

1) Remove the todo, ING coming doesn't provide usefull information
2) yield account instead to create a list
3) remove coming in the test (not implemented)

modules/ing/test.py

@@ -28,5 +28,4 @@ class INGTest(BackendTest):
         l = list(self.backend.iter_accounts())
         if len(l) > 0:
             a = l[0]
-            list(self.backend.iter_coming(a))
             list(self.backend.iter_history(a))