Move cacert/insecure awkwardness examples/common

The requests.Session object that transport derives from has
this overloaded meaning for verify that is causing awkwardness
around our code.  I've moved the ugly to the examples/common.py
argument parsing.

Change-Id: I3e8f5311eeba6108d3ea086a01b71663401a52fa
Merge "Move cacert/insecure awkwardness examples/common"