add IPython version to session header

will allow future logic to make appropriate compatibility checks

IPython/zmq/session.py

@@ -43,6 +43,7 b' from zmq.utils import jsonapi'
 from zmq.eventloop.ioloop import IOLoop
 from zmq.eventloop.zmqstream import ZMQStream
 
+import IPython
 from IPython.config.application import Application, boolean_flag
 from IPython.config.configurable import Configurable, LoggingConfigurable
 from IPython.utils.importstring import import_item
@@ -74,7 +75,7 b' def squash_unicode(obj):'
 # globals and defaults
 #-----------------------------------------------------------------------------
 
-
+_version_info_list = list(IPython.version_info)
 # ISO8601-ify datetime objects
 json_packer = lambda obj: jsonapi.dumps(obj, default=date_default)
 json_unpacker = lambda s: extract_dates(jsonapi.loads(s))
@@ -187,6 +188,7 b' class Message(object):'
 
 def msg_header(msg_id, msg_type, username, session):
     date = datetime.now()
+    version = _version_info_list
     return locals()
 
 def extract_header(msg_or_header):