fixes recreating initial journals

the method now uses the acts_as_journalized methods
when recreating the initial journal and tries to use
existing journals for rebuilding the history

--HG--
extra : source : f6bd10bc46179871d43ac619abc1f5b52eaa4d2e
rename journal#changes attribute to changed_data

--HG--
extra : source : 660a6db6ade27d1b5c4e0b36f9e82e5599f4dcf6
REVIEW: another batch of the renaming effort from Journals#changes to changed_data

--HG--
extra : source : f87c5376f44f3b6d73ac223184fdbe4a6e6dee11