Log Message:
py-urllib3: updated to 1.23

1.23:
* Allow providing a list of headers to strip from requests when redirecting
  to a different host. Defaults to the Authorization header. Different
  headers can be set via Retry.remove_headers_on_redirect.
* Fix util.selectors._fileobj_to_fd to accept long
* Dropped Python 3.3 support.
* Put the connection back in the pool when calling stream() or read_chunked() on
  a chunked HEAD response.
* Fixed pyOpenSSL-specific ssl client authentication issue when clients
  attempted to auth via certificate + chain
* Add the port to the connectionpool connect print
* Don't use the uuid module to create multipart data boundaries.
* read_chunked() on a closed response returns no chunks.
* Add Python 2.6 support to contrib.securetransport
* Added support for auth info in url for SOCKS proxy