migrate to int ids for location primary key + manual event_name

migrate to int ids for location primary key + manual event_name

Rather than generating the event name from the id/type of the location
we've instead made the id's autoincrementing integers with a custom
event_name field that defines the event they trigger.

It makes it a lot easier to build generic functionality and we can
always swap the id's to uuids if we really care that much.