Bug fixes for Security Groups

RM10897

Updates the redis_client and redis_sg_tool based on manual testing. Also
reworks the connection semantics to defer to the sentinel class itself
for the connection pooling.Finally, removes all SSL connection
semantics, as it was determined that Sentinel connections and SSL do
not easily mix, and thus none of the existing implementation could
work as is.

A bit moot post-merge, but json.loads could return almost any data type besides a set or tuple. Making it None is potentially the clearest way to emphasize nothing, depending on your intent.