[FIX] OPW 598942 : orm read_group doesn't take referenced fields or aggregated fields...

[FIX] OPW 598942 : orm read_group doesn't take referenced fields or aggregated fields in account when sorting
Sorting was done using a search on ids that where found in a custom SQL field,
only 1 record among aggregated records with same groupby value was used
when using search for ordering, resulting data ordered on
max(aggregated_data).field_value instead of sum(aggregated_data.field_value).

lp bug: https://launchpad.net/bugs/1060086 fixed

bzr revid: acl@openerp.com-20140217172926-ka2fw8t2l3cqi7h3