Allow setting a location for a Device - so all feed data is tagged with Location metadata

We'll have GPS eventually, but for a lot of WipperSnapper devices they are expected to be at static locations. We could improve the mapping potential of non-GPS wippersnapper devices by allowing users to configure a Latitude and Longitude on the Device Settings page (where sleep timer is set).

Start at the Device Settings page, where the sleep timer is set, and trace how device configuration reaches feed data. Done means users can save Latitude and Longitude for a static device and resulting feed data carries Location metadata, including for devices without GPS.

Written by the indexing model from the issue text.