This commit adds the tls_enabled parameter to the conf_dict, so to eventually use it in the backend driver. In addition, it switches from _memcache_pool.MemcacheClientPool to _bmemcache_pool.BMemcacheClientPool when tls_enabled=true (python-memcached does not support tls anyway). Jira: https://issues.redhat.com/browse/OSPRH-16651 Change-Id: I1ceac2aa96c23227caf202b16f9a520083745537