Add new change state "deferred".

Support for new change state "deferred" to be able to discern
"really dead" from "postponed" changes. This is equal to "abandoned"
for all practical purposes except presentation and filtering. State
transitions are possible between "review in progress", "abandoned"
and "deferred". And menu bar has new "All/deferred" and "My/Deferred
Changes" default filters.

Task-number: QTQAINFRA-598
Change-Id: I57b4f716fb826c5f246d02463b1ed9c75c4d04ae
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>