key paramiko ssh cache on port

This supports different SSH ports for different hosts.  Not currently used but
needed to support using hostvars for connection settings (i.e. ssh port setting
via hostvar).
copy variables from runner to connection

This currently doesn't change any functionality.  Not currently used but needed
to support using hostvars for connection settings (i.e. ssh password / user
settings via hostvar).
allow ssh user / password as a per-host variable