Fix changing tuner-type

Fix the issue of changing the tuner type and hitting save doing nothing. Also make it rebuild the page for the new tuner type so you don't have to restart tvheadend.
device_id was never actually set, the field displayed in the gui (which value was always 0) was called UUID, and uuid was actually populated with a value. Could just remove the whole section if UUID is/will be obsolete. I don't think it actually provides any relevant information.