Resolve "Manage clients"

Closes #2 (closed)

There's an issue with WebSockets - after the configuration is downloaded, WS connection is closed. This causes some features to break, like refreshing the list of registered clients after the client access is revoked. I wish to deal with it as a separate ticket since this one is already too big. https://gitlab.labs.nic.cz/turris/reforis/reforis/issues/138