A follow-up on c2a8cbe7f4c2bfce3720c0597ae076b2a4142bbd. This commit
will update event payload json schema to better match the data it will
store. Additionally it adds counter cache for error event model.
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Changelog: changed
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>