Update object hierarchy read/write to support the KMIP version

This change updates the PyKMIP object hierarchy's read/write
method signatures to support propagation of the KMIP version. The
introduction of KMIP 2.0 introduces future KMIP message encodings
that break backwards compatibility; to support this, PyKMIP must
know what KMIP version is being used when encoding or decoding an
object; the KMIP version residing in the client or server alone
is now insufficient. Prior versions of KMIP, namely 1.0 - 1.4,
have been backwards compatible, obviating the need for the KMIP
version at encode/decode time. Going forward, this is no longer
true.

The PyKMIP client and server have been updated to include the
KMIP version when making calls to read/write, as have the
associated test cases covering this functionality.

kmip/tests/unit/services/server/test_engine.py

@@ -213,7 +213,7 @@ class TestKmipEngine(testtools.TestCase):
             batch_items=batch
         )
 
-        response, max_size = e.process_request(request)
+        response, max_size, protocol_version = e.process_request(request)
 
         e._logger.info.assert_any_call(
             MockRegexString("Received request at time:")