Upgrade OpenPGP applet to 1.0

Originally created by @intrigeri on #11899 (Redmine)

openpgp-applet 1.0 was uploaded to sid (#7711 (closed)). We should backport it for Jessie, test it in there, and upgrade to 1.0-1~bpo8+1 e.g. in Tails 2.8.

Related issues

Blocked by #7711 (closed)

Edited May 15, 2020 by intrigeri

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