Filesystem-based dispatcher and runner for development environments

Makes it possible for multiple apps to communicate with each other, without
having to have an AMQP (RabbitMQ) service running. This should make it easy
to run Woodhouse-based apps in both production and development environments.

For rails, add the following to your config/initializers/woodhouse.rb:

    Woodhouse.configure do |woodhouse|
      # general / production woodhouse setup...

      if Rails.env.development?
        woodhouse.dispatcher_type = :file
        woodhouse.runner_type = :file

        # optional, overrides the location of the queue
        woodhouse.server_info = {
          path: '/tmp/woodhouse/queue',
        }
      end
    end