[translation] fix: day -> savedDate field (Zanata)
[translation] fix: day -> savedDate field (Zanata)

Currently all Zanata API responses within the same week
are saved as Stackalytics records with the same day,
which results on wrong translation statistics.

Zanata 'savedDate' fields are appropriate for 'date' fields
on translation records. So the change from day to 'savedDate' is
needed for correct statistics.

Change-Id: I5f804c306deb30db41febd94ea6038232a32a3c6

stackforge/stackalytics,0xf2/stackalytics,0xf2/stackalytics,Mirantis/stackalytics,Mirantis/stackalytics,openstack/stackalytics,0xf2/stackalytics,stackforge/stackalytics,openstack/stackalytics,stackforge/stackalytics,openstack/stackalytics,Mirantis/stackalytics,0xf2/stackalytics,openstack/stackalytics