Reap dead devices using timeouts. Previously, if a provider died without being able to clean up properly, the device would stay as a ghost.

lib/roles/processor.js

@@ -65,6 +65,9 @@ module.exports = function(options) {
         })
     })
     // Worker messages
+    .on(wire.DeviceHeartbeatMessage, function(channel, message) {
+      dbapi.updateDeviceHeartbeat(message.serial)
+    })
     .on(wire.JoinGroupMessage, function(channel, message, data) {
       dbapi.setDeviceOwner(message.serial, message.owner)
       appDealer.send([channel, data])