Add support for disabling SSL host name verification

There are some use-cases where SSL certificate verification is required, but without validating the CN (it is the host name of the server in HTTPS).

This patch introduces the dont_verify_host flag, which disables host verification, only if it is set to True. A value of None (the default) or False will keep the enabled host verification.

Signed-off-by: Boris Figovsky <boris.figovsky@ravellosystems.com>