If node class has an auto_create_connection method, then use that for…

[clive-devops]

This allows a developer to define Docker::Swarm::Node#auto_create_connection in which node connections can be created as needed.

class Docker::Swarm::Node
  def self.auto_create_connection( node_instance )
    # use node_instance to create and return a connection
  end
end

Fixes #10