Raise NotImplementedError instead of NotImplemented

NotImplementedError is the name of the exception
(https://docs.python.org/2/library/exceptions.html).
NotImplemented is the name of a constant
(https://docs.python.org/2/library/constants.html).
>>> raise NotImplemented()
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    raise NotImplemented()
TypeError: 'NotImplementedType' object is not callable
>>> raise NotImplementedError()
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    raise NotImplementedError()
NotImplementedError
This patch fix it.

Change-Id: I939eaa4b4b7c574f7a6447725e3a6ad5b128f1b7
Closes-Bug: #1339855

heat/engine/environment.py

@@ -154,7 +154,7 @@ class ResourceInfo(object):
         return False
 
     def get_class(self):
-        raise NotImplemented
+        raise NotImplementedError
 
     def get_class_to_instantiate(self):
         return self.get_class()

heat/tests/test_resource.py

@@ -1193,7 +1193,7 @@ class ResourceTest(common.HeatTestCase):
         prop_diff = {'Foo': 'xyz'}
         self.m.StubOutWithMock(generic_rsrc.ResourceWithProps, 'handle_update')
         generic_rsrc.ResourceWithProps.handle_update(
-            utmpl, tmpl_diff, prop_diff).AndRaise(NotImplemented)
+            utmpl, tmpl_diff, prop_diff).AndRaise(NotImplementedError)
         self.m.ReplayAll()
         updater = scheduler.TaskRunner(res.update, utmpl)
         self.assertRaises(exception.ResourceFailure, updater)