Miscellaneous fixes

This release features a bunch of improvements with the captive portal functionality thanks to @timrettop -- namely it adds a ENABLE_CAPTIVE setting in the environment file that will import the certificate and restart the unifi-os container regardless of certificate age on reboot. This fixes issues where post reboot the captive portal would revert back to a self-signed certificate.

Those upgrading from previous versions should take note that there are significant changes in the udm-le.env file that require updating your existing installation or this script will fail to function.