Add dummy runner internal plugin and skip on plugin install commands.
Add postinstall feature to runner plugins & add dummy runner plugin.

A runner plugin would add postinstall logic by adding a `postinstall'
block in thir class like so:

    class Busser::RunnerPlugin::MyPlugin < Busser::RunnerPlugin::Base

      postinstall do
        empty_directory("#{root_path}/secrets")
        create_file("#{root_path}/secrets/credentials.txt")
        banner("Printing secrets")
        run!("cat #{root_path}/secrets/*.txt >/dev/null")
        say("Or did I?")
      end
    end

Notice that all helpers from Busser::RunnerPlugin::Base will be
available as are all Thor actions.