Removing useless methods

At first, I saw that the changes list was being sorted by the revisions, and thought that because of that
it will be necessary to allow sorting by time for the other VCSs. But, then I realized that the sorting
was being done simply so that duplicate changes with same revision will be grouped for removing. This works
no matter if the revision is a number or not.

buildbot/status/web/console.py

@@ -786,20 +786,11 @@ class RevisionComparator(object):
 
     def isRevisionEarlier(self, first, second):
         raise NotImplementedError
-
-    def getSortingKey(self):
-        raise NotImplementedError
 
 class TimeRevisionComparator(RevisionComparator):
     def isRevisionEarlier(self, first, second):
         return first.when < second.when
 
-    def getSortingKey(self):
-        return operator.attrgetter('when')
-
 class IntegerRevisionComparator(RevisionComparator):
     def isRevisionEarlier(self, first, second):
         return int(first.revision) < int(second.revision)
-
-    def getSortingKey(self):
-        return operator.attrgetter('revision')

buildbot/test/test_console.py

@@ -68,16 +68,6 @@ def testOrdersDifferentRevisions(self):
         self.assertTrue(self.comparator.isRevisionEarlier(first, second))
         self.assertFalse(self.comparator.isRevisionEarlier(second, first))
 
-    def testReturnedKeySortsRevisionsCorrectly(self):
-        my_changes = [_createDummyChange('rev' + str(i))
-                      for i in range(1, 6)]
-        for i in range(1, len(my_changes)):
-            my_changes[i].when = my_changes[i-1].when + 1
-
-        reversed_changes = list(reversed(my_changes))
-        reversed_changes.sort(key=self.comparator.getSortingKey())
-        self.assertEqual(my_changes, reversed_changes)
-
 class IntegerRevisionComparatorTest(unittest.TestCase):
     def setUp(self):
         self.comparator = console.IntegerRevisionComparator()
@@ -93,13 +83,6 @@ def testOrdersDifferentRevisions(self):
         self.assertTrue(self.comparator.isRevisionEarlier(first, second))
         self.assertFalse(self.comparator.isRevisionEarlier(second, first))
 
-    def testReturnedKeySortsRevisionsCorrectly(self):
-        my_changes = [_createDummyChange(str(i)) for i in range(1, 6)]
-
-        reversed_changes = list(reversed(my_changes))
-        reversed_changes.sort(key=self.comparator.getSortingKey())
-        self.assertEqual(my_changes, reversed_changes)
-
 # Helper class to mock a request. We define only what we really need.
 class MockRequest(object):
     def childLink(self, link):