Revert DynamicChangelog for new mGerrit generated changelog

mGerrit provides a truely dynamic changelog delimited
by user selection. We pull from Gerrit then provide
results based on a Date range. Date range is determined
when user selects a nightly build (parsed from goo.im)
from their devices list. The app then delimits the merged
list using the selected build's upload date as the
ceiling and the previous nightly build's upload date
as the floor.

This method has several benifits

1) NO external servers, cron jobs, scripts or headaches required
   We can complete all the calculations on device (and quickly).
2) This method is completely user driven, they select
   which changelog to build.
3) This method is very specific. This isn't a list of everything
   committed before the selected date. The changelog show
   is only the merged commits within the time range.
4) This way is user agnostic, We open up your devices nightly
   folder (goo.im) to allow you to download the zip or
   view its changelog.
   *This should work for all (read all aokp supported) devices
5) This way is much prettier :P

Patch Set 2: update commit message to reflect mGerrit's
             current behavior

Change-Id: I72933c9bf4842be430d77f2711b52272dc62dfdc