Time End of deployment is different in notifications

[Julia Aranovich]

Steps to reproduce in Fuel UI:

1. deploy environment with some node(s)
2. go to History tab and check the deployment summary: time end attribute
3. then go to Notifications page and check time of notification about the finished deployment.

Expected result: times should be the same.
Actual result: time in the notification is incorrect (3 hours less for my timezone).

Solution here should be using of the same format of time attribute output as for deployment tasks, transactions.

So, now notification time comes as "08:41:21", but should be "2016-09-08T07:00:58.702879" (ISO8601 date)