Bugfixes to serial/records management, Supervisor support for Linux

This release brings two improvements and one notable regression:

• zeronsd supervise and zeronsd unsupervise can be used to automatically join a zeronsd to your network through systemd. Must be on linux and using systemd to use appropriately.
• Several issues with managing the catalog were fixed.
• IPv6 support is currently on further hold until 0.2.x ships. This is because it needs a significant rework for how users use IPv6 with zerotier. We apologize if there is anyone depending on the existing functionality; for what it's worth, it should improve soon.
• Diagnostics for when records are added/removed to the catalog were also added.