check zmq version at top-level kernel import

maybe someday this won't be necessary, but it is now.

IPython/kernel/__init__.py

@@ -1,5 +1,8 b''
 """IPython kernels and associated utilities"""
 
+# just for friendlier zmq version check
+from . import zmq
+
 from .connect import *
 from .launcher import *
 from .kernelmanager import KernelManager