history: fixed users external_id type due to engine change

external_id feild changed to type text on engine.
update etl and history db accordingly.

Change-Id: I328a5d27ca90eb4ebb338cedf41fe9d0e4f49f7e
Bug-Url: https://bugzilla.redhat.com/1113193
Signed-off-by: Shirly Radco <sradco@redhat.com>