Consider providing checksums for the release files

[saadkadhi]

Request Type

Feature Request

Problem Description

As described in TheHive-Project/TheHive#590, ensure that Cortex packages have associated SHA256 or similar hashes that can be independently checked by administrators before deploying the app. Give also the means to check the PGP sig.

[saadkadhi]

We already provide PGP-signed RPMs and DEBs but we should definitely extend that to bin packages and possibly add SHA256 sums if lazy folks don't want to put up with the PGP PITA.

The PGP pubkey is located at https://github.com/TheHive-Project/Cortex/blob/master/PGP-PUBLIC-KEY.