set_address: New method for specifying units address for net-splits
deployments
send_all: Send setting to all peers
retrieve_local: Retrieve key from local db
retrieve_remote: Retrieve key from peers
Fix name of interface.yaml (should not be plural)
Fix tox targetss and drop charm-tools from requirements
Change-Id: I4b0b952c3490cb7c0a877cd827333d69e81ebdab