Update device instead of upsert so that we don't lose data between unplugs.

lib/db/api.js

@@ -52,20 +52,24 @@ dbapi.saveDeviceLog = function(serial, entry) {
 }
 
 dbapi.saveDevice = function(serial, device) {
-  return db.run(r.table('devices').insert({
-      serial: serial
-    , present: true
-    , provider: device.provider
-    , owner: null
-    , status: device.status
-    , ready: false
-    , statusChangedAt: r.now()
-    , createdAt: r.now()
-    , lastHeartbeatAt: r.now()
-    }
-  , {
-      upsert: true
-    }))
+  var data = {
+    present: true
+  , provider: device.provider
+  , owner: null
+  , status: device.status
+  , ready: false
+  , statusChangedAt: r.now()
+  , createdAt: r.now()
+  , lastHeartbeatAt: r.now()
+  }
+  return db.run(r.table('users').get(serial).update(data))
+    .then(function(stats) {
+      if (stats.skipped) {
+        data.serial = serial
+        return db.run(r.table('devices').insert(data))
+      }
+      return stats
+    })
 }
 
 dbapi.saveDeviceStatus = function(serial, status) {