add helper functions for python3 support

This functions are used in the whole code and are
mandatory for the python3 support to work. In python2
case nothing is touched.

* cmp_to_key:
  converts a cmp= into a key= function

* decode_list:
  decodes each element of a list. This is needed if
  we have a mixed list with strings and bytes.

* decode_it:
  Takes the input and checks if it is not a string.
  Then it uses chardet to get the encoding.

tests/test_helpers.py

@@ -0,0 +1,35 @@
+import unittest
+from osc.util.helper import decode_it, decode_list
+
+def suite():
+    return unittest.makeSuite(TestResults)
+
+class TestResults(unittest.TestCase):
+    def testDecodeList(self):
+        strlist = ['Test1', 'Test2', 'Test3']
+        mixlist = ['Test1', b'Test2', 'Test3']
+        byteslist = [b'Test1', b'Test2', b'Test3']
+
+        out = decode_list(strlist)
+        self.assertListEqual(out, strlist)
+
+        out = decode_list(mixlist)
+        self.assertListEqual(out, strlist)
+
+        out = decode_list(byteslist)
+        self.assertListEqual(out, strlist)
+
+
+    def testDecodeIt(self):
+        bytes_obj = b'Test the decoding'
+        string_obj = 'Test the decoding'
+
+        out = decode_it(bytes_obj)
+        self.assertEqual(out, string_obj)
+
+        out = decode_it(string_obj)
+        self.assertEqual(out, string_obj)
+
+if __name__ == '__main__':
+    unittest.main()
+