3.1.12 fixes

[dgilman]

• Re-added the travis.yml. Not sure what happened with the old one but sounds like some git magic made it disappear
• Changed the github token. Either I deleted my old one on accident or you switched it to your personal one. Either way it's currently set to a dgilman/netatalk-debian token.
• Removed oldstable (jessie) builds as they can't parse the pristine-tar format anymore

And the big one:

• Bumped debian/control to libgcrypt20-dev. The old package appears not to be available in any form in testing (buster) so this fixed the build there.

For testing, I fired this up on my stable (stretch) server and it seemed to work fine. I'm listening to mp3s getting streamed by 3.1.12 debs right now in fact.