Port to Drupal 8

Opening an issue for discussion about the port to D8.

I've started the port (from 7.x-1.1) in https://github.com/mjl3475/townsec_key which utilizes my Encrypt port https://github.com/mjl3475/encrypt and the Key Module by @nerdstein https://github.com/nerdstein/key as Plugin Managers for Keys and Encryption Methods.