Install the Dekko email app by default

[Pat McGowan]

List of dependencies 7/22

Fixed:
Bug #1378330 Should integrate with online accounts
Bug #1473776 Recipient email address disappears when forwarding an email
Bug #1462006 Infinite dialog loop for invalid email address
Bug #1478822 No option for non-authenticated SMTP
Bug #1446578 Blank offline allmail front page when Dekko starts
Bug #1503670 IMAP setup should prompt to ask inclusion of SMTP config when autoconfig fails

Todo:
https://bugs.launchpad.net/dekko/+bugs?field.tag=default

Bug #1421923 No notifications for new mails
Bug #1497292 Yahoo online accounts integration.

[Dan Chapman  (dpniel)]

I've marked bug #1425949 as no longer being a critical bug in Dekko.

We currently support importing multiple contacts through content-hub to a local address-book which provides direct searching of contacts. This is also inline with how telegram imports contacts.

Although bug #1425949 would be a nice feature to have, in my opinion it's no longer a blocker for Dekko.

[Łukasz Zemczak (sil2100)]

So this is now officially done since at least a week. Click-sync is syncing it by default and uploading to the ubuntu custom tarballs. All other vendor-specific device tarballs have been updated as well.