Start all plugins.

@param program Program or Plain object.
@param app Express app.
@param callback Termination.
function (program, app, callback) {
    var attachPlugin = function (pluginName, cb) {
      pluginHelpers.start(pluginName, program, app, cb);
    };

    var plugins = Object.keys(pluginHelpers.loadedPlugins)
    async.eachSeries(plugins, attachPlugin, function() {
      callback();
    });
  }