Turn on email bundling for post edit/reply + instructions

To test this on a local environment, this will need:

1. set the time interval in $wgEchoBundleEmailInterval between sending
   emails, by default it's zero and disable email bundling

2. Config with a redis job queue, I think only redis support
   delayed job queue

3. config the bundle email job with something like:
   $wgJobTypeConf['MWEchoNotificationEmailBundleJob'] = array(
	'class'       => 'JobQueueRedis',
	'redisServer' => '127.0.0.1',
	'redisConfig' => array( 'connectTimeout' => 1 ),
	'claimTTL'    => 3600,
	'checkDelay'  => true
  );

Change-Id: I76d08706cdd90fe0cd2fd745c36bf50f9b7672d3