Resigning; previous key revoked.
Added a utility to restart the server on changes.

The utility itself needs to be restarted to watch new directories;
doing so automatically is annoying.
Fixed a few silly oversights in develop.js.

 - A process exiting early shouldn’t cause problems with `kill`
 - A function throttled to a certain rate shouldn’t ignore
   its most recent calls when they fall within the threshold
Updated dependencies.
Added migration for sessions.
Use standard ES6 Promise functions.
ENOTDIR isn’t consistent; have an ugly hack.
Merge remote-tracking branch 'upstream/master'