add ssl support for redis with sentinel

[cyberjunk]

redbeat can already connect to sentinel using tls by setting sentinel_kwargs in redbeat_redis_options accordingly, e.g.:

'sentinel_kwargs': { 'ssl': True, 'ssl_cert_reqs': ssl.CERT_NONE }

this will be passed to the Sentinel() constructor and works fine for the connection from redbeat to sentinel.

however, this is only one of the two connections made from redbeat in a redis+sentinel setup...
the next connection which is made to the returned redis master afterwards was always without tls.

to make the connection to redis also use tls, one has to pass the according ssl related connection_kwargs to Sentinel() constructor.

I adapted the code from the encrypted rediss case below:
checking if redis_use_ssl is defined, and if so, set ssl to True and inject the parameters provided in redis_use_ssl for the connection from redbeat to redis. this way redbeat can be configured to use tls on both, the sentinel AND the redis connection using existing configuration settings and it's working fine for me now...