[Merge] lp:~tiagosh/messaging-app/state-saver2 into lp:messaging-app

[Tiago Salem Herrmann]

This MR is currently on hold. There was a sdk limitation that made it impossible to land this MR. 
Problem is that this branch is rather old and trunk code is quite different now.
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https://code.launchpad.net/~tiagosh/messaging-app/state-saver2/+merge/250996
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