[Feature] Add Sync GPG/PGP Keys to Mailspring Pro

[asddsaz]

Feature: Add sync GPG/PGP Keys to Mailspring Pro.
Why? I personally, find it annoying to sync and renew PGP keys on all devices. This could take that annoyance away. Of course, for security reasons it should be E2E encrypted.

Note: Part of #25

[bengotow]

Hey! I think this is a great idea—we would probably want to investigate whether this could be handled by https://keybase.io/ as well. The E2E encryption (and more critically cloud storage) of keys isn't something I'd want to take on lightly! (We currently don't sync mail accounts or passwords through the cloud because the potential for exploit is so high.)

[marxistvegan]

Good idea but can we make this a non-pro feature for those of us that are not part of an organization with a budget please.

[loiner]

Agreed, @marxistvegan. Basic privacy options shouldn't be paywalled.

[bengotow]

Merging into #25 so we can track development of this in one place!

[prozumr]

Mailspring looks very nice and promising. But no support for GPG is a showstopper. Whenever GPG is integrated I will switch immediately to mailspring. Until then I go back to Evolution.