need API for managing passwordless authentication for ctdb integration

Part of the ctdb stack is an administrative utility called "onnode" which has the ability of running commands on all nodes in the ctdb cluster. The "onnode" utility simply uses ssh or rsync to communicate with the nodes.

If passwordless authentication isn't setup between the nodes, then the "onnode" utilty will block waiting on stdin for the password to be entered for each node in the cluster.