Create a SerializableComparable class

Create a SerializableComparable class derived from the Serializable
class.

Added the following functions to the SerializableComparable class:
  '__eq__'
  '__ne__'

Disable the '__hash__' function in the SerializableComparable class as
some derived classes are mutable.

Use the SerializableComparable class in hardware.py and
extensions/base.py

This should make unit testing users of the class easier when doing a
self.assertEqual() or self.assertNotEqual()

Added some initial unit testing for encoding.py

Change-Id: If0f14b3bfe7f1391f65dd730a16a534afed0da82

ironic_python_agent/tests/unit/test_encoding.py

@@ -0,0 +1,62 @@
+#    Copyright (C) 2015 Intel Corporation
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslotest import base as test_base
+
+from ironic_python_agent import encoding
+
+
+class SerializableTesting(encoding.Serializable):
+    serializable_fields = ('jack', 'jill')
+
+    def __init__(self, jack, jill):
+        self.jack = jack
+        self.jill = jill
+
+
+class SerializableComparableTesting(encoding.SerializableComparable):
+    serializable_fields = ('jack', 'jill')
+
+    def __init__(self, jack, jill):
+        self.jack = jack
+        self.jill = jill
+
+
+class TestSerializable(test_base.BaseTestCase):
+    def test_baseclass_serialize(self):
+        obj = encoding.Serializable()
+        self.assertEqual({}, obj.serialize())
+
+    def test_childclass_serialize(self):
+        expected = {'jack': 'hello', 'jill': 'world'}
+        obj = SerializableTesting('hello', 'world')
+        self.assertEqual(expected, obj.serialize())
+
+
+class TestSerializableComparable(test_base.BaseTestCase):
+
+    def test_childclass_equal(self):
+        obj1 = SerializableComparableTesting('hello', 'world')
+        obj2 = SerializableComparableTesting('hello', 'world')
+        self.assertEqual(obj1, obj2)
+
+    def test_childclass_notequal(self):
+        obj1 = SerializableComparableTesting('hello', 'world')
+        obj2 = SerializableComparableTesting('hello', 'world2')
+        self.assertNotEqual(obj1, obj2)
+
+    def test_childclass_hash(self):
+        # Ensure __hash__ is None
+        obj = SerializableComparableTesting('hello', 'world')
+        self.assertEqual(None, obj.__hash__)