Valetudo 0.3.1-RE3 preview

Third release for testing RE version, verified on S55 (fw 1864).

Mostly bugfix release:

• Hopefully fixed dynamic auth middleware, now it should be really dynamic and not requires to restart Valetudo anymore for changes to take effect;
• Some visual improvements for zones editing, active locations now can be deselected, zone "promotion" button now should appear on the map only when it makes sense;
• Attempted to fetch updated virtual walls & forbidden zone locations a bit quicker after editing them; also added a (debug) button that tries to forcefully reload the map.

Also includes all upstream updates till 24 jun 2019.