embed_kernel: pass [] to IPKernelApp.initialize to prevent argv parsing

https://github.com/ipython/ipython/pull/1357/files#r400153
Stop embed_kernel() from parsing sys.argv since to support being called from
a environments with their own command line args.

IPython/zmq/ipkernel.py

@@ -660,7 +660,7 b' def embed_kernel(module=None, local_ns=None):'
     if local_ns is None:
         local_ns = caller_locals
     app = IPKernelApp.instance(user_module=module, user_ns=local_ns)
-    app.initialize()
+    app.initialize([])
     app.start()
 
 def main():