Improvements and fixes

Changing a plant's VPN settings and issuing a fresh certificate is now one step instead of two.

• On a VPN connection, "Apply changes & rotate certificate" applies the waiting settings and issues a fresh certificate in one step.
• An OpenVPN option on a plant's VPN connection set back to its default value is now saved instead of being lost.
• Opening the web app while still signed in now goes straight in instead of showing the sign-in page.
• The API history can now be narrowed to the calls that changed something with "Non-GET".