Support for TLS connections and fix TTL

[jcalonso]

Hi there!
I recently used this project to do some migrations from ElastiCache. While doing this I came a cross 2 problems.

1. There was a bug with the TTL not being reset to 0 when the key didn't have any set.
2. There wasn't a way to use TLS connections.

I made those changes in this fork: master...jcalonso:patch-1
I would be happy to open a proper pull request and merge this back if you consider this is something of use in the project.

Let me know :)