use stdlib json to load connection files in zmq.kernelmanager

prevents longs from causing a TraitError

See 64e90b1e

IPython/zmq/kernelmanager.py

@@ -17,6 +17,7 b' TODO'
 
 # Standard library imports.
 import errno
+import json
 from Queue import Queue, Empty
 from subprocess import Popen
 import os
@@ -29,7 +30,6 b' import time'
 import zmq
 from zmq import POLLIN, POLLOUT, POLLERR
 from zmq.eventloop import ioloop
-from zmq.utils import jsonapi as json
 
 # Local imports.
 from IPython.config.loader import Config