Commit 35d41dbb0e changed the API for using
SSL with umqtt, but only did a minor version increase. This broke various
uses of this library, eg
https://github.com/aws-samples/aws-iot-core-getting-started-micropython
Reinstate the original API for specifying an SSL connection. This library
now supports the following:
- default, ssl=None or ssl=False: no SSL
- ssl=True and optional ssl_params specified: use ssl.wrap_socket
- ssl=<SSLContext instance>: use provided SSL context to wrap socket
Signed-off-by: Damien George <damien@micropython.org>