if con_cache is inactive, dont create con_cache-client

If max_minions is used with an inactive con_cache-setting, the MWorkers will block in Clearfuncs._auth() while trying to connect to the con_cache which was not started.

This change checks for an active con_cache-setting, then creates the con_cache-client. 

Else set cache_cli=False to have the MWorkers use CkMinions.connected_ids() instead of the con_cache.