Add session encoding debug logging to the server

This change adds debug logging statements for the request and
response message encodings sent and received by the server
session. These provide direct visability into each message that
is handled by the server, facilitating debugging and correctness
checking. Given the content of these encodings may contain
sensitive information, debug logging should only be enabled when
testing or developing server features.

kmip/services/server/session.py

@@ -13,6 +13,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import binascii
 import logging
 import socket
 import struct
@@ -345,8 +346,14 @@ class KmipSession(threading.Thread):
                 "does not match the advertised header length."
             )
         else:
+            self._logger.debug(
+                "Request encoding: {}".format(binascii.hexlify(message))
+            )
             return message
 
     def _send_response(self, data):
         if len(data) > 0:
+            self._logger.debug(
+                "Response encoding: {}".format(binascii.hexlify(bytes(data)))
+            )
             self._connection.sendall(bytes(data))