Add :name to periodically_call_remote

In our project, we had to assign a variable name to periodically_call_remote, so that we could manipulate it using rjs/javascript (for instance, calling stop()). I changed the periodically_call_remote to include a :name parameter, to generate this:

var updater = new PeriodicalExecuter(function() {new Ajax.Updater('news_block', 'update', {asynchronous:true, evalScripts:true})}, 20)

instead of simply

new PeriodicalExecuter(function() {new Ajax.Updater('news_block', 'update', {asynchronous:true, evalScripts:true})}, 20)

(the name is configurable, of course)

Hope it's useful for anyone else..