Heroku Changelog Newly created apps have a different log auto split length of 10k bytes

Change effective on 07 April 2014

The old log path auto-split log-lines every 1k bytes, the new log path auto-splits log lines every 10k bytes. We are working on a schedule to flag all apps onto the new log path in the future.

NOTE: Apps in the EU have had this feature silently turned on since the start of the EU region.

Log Formatting docs updated.