[patch] AR::Base Reverse find_in_batches.

i see the point of the order thing, but not of the limit - there is already a batch size ?

tested with mysql - the tests run, but i would add test with :order => :asc too. I know that's the default too, but someone's bound to specify it if the option exists (in the foolproof category).

tested the (only slightly) modified patch with
mysql
postgresql
sqlite3

with ruby1.8.6

for ruby1.9.1:
activerecord/lib/active_record/attribute_methods/read.rb:15:in undef_method': undefined methodid' for class ActiveRecord::Base' (NameError)<br/> probably due to something else, and it occurs with all above dbs.