Build: Monkeypatch nose to support python3 (#2779)

In python3:
  collections.Callable -> collections.abc.Callable

So we test for collections.Callable and then monkeypatch collections if it's not there

testing/testing.py

@@ -104,6 +104,14 @@ def run_tap(self, module):
         tr.run(tests)
 
     def run_nose(self, module_name):
+        import collections
+
+        try:
+            collections.Callable
+        except:
+            import collections.abc
+            collections.Callable = collections.abc.Callable
+
         import nose
         import shutil
         f = self.test_format