APNS: Add log message with number of devices sent to

Add a log message indicating number of devices the payload is being sent to.  This is similar to the log message generated by the GCM sender.  Clean up spacing.
Good point.  I was just being consistent with the logging in the GCM sender.  As well as other areas.  Like the following:

When a device registers:
2014/05/21 15:22:16,973 INFO  [org.jboss.aerogear.unifiedpush.rest.registry.installations.InstallationRegistrationEndpoint] (http-127.4.120.1-127.4.120.1-8080-1) Updating received metadata for Installation

When a message is sent:
2014/06/11 11:20:00,927 INFO  [org.jboss.aerogear.unifiedpush.rest.sender.PushNotificationSenderEndpoint] (http--127.4.120.1-8080-1) Message submitted to PushNetworks for further processing
2014/06/11 11:20:00,952 INFO  [org.jboss.aerogear.unifiedpush.service.sender.impl.SenderServiceImpl] (EJB default - 3) Processing send request with 'UnifiedPushMessage [criteria=[aliases=null, deviceTypes=null, categories=null, variants=null], simplePush=null, alert=Testing 82, sound=null, badge=1, data={alias=[18856]}, time-to-live=-1]' payload