Evaluate GnuPG trustlevel for signature check and print signer names
Created originally on Bitbucket by Anonymous
Was already merged in Bitbucket before import, marked as merged by the import user
This extends the commitsigs script to print the signer name next to the good X signature to show who really signed the commit. The functionality is implemented for both openssl and gnupg.
Also, it is possible to require a minimum trust level for gnupg signatures (defaulting to TRUST_UNDEFINED if not configured, so it is optional).