Better device present/absent handling by separating it from the status event.

lib/db/api.js

@@ -41,26 +41,36 @@ dbapi.saveDeviceLog = function(serial, entry) {
   }))
 }
 
-dbapi.saveDeviceStatus = function(serial, status) {
-  return db.run(r.table('devices').get(serial).update({
-      status: status.status
-    , provider: status.provider
+dbapi.saveDevice = function(serial, device) {
+  return db.run(r.table('devices').insert({
+      serial: serial
+    , present: true
+    , provider: device.provider
+    , status: device.status
     , statusChangedAt: r.now()
+    , createdAt: r.now()
+    }
+  , {
+      upsert: true
     }))
-    .then(function(stats) {
-      if (stats.skipped) {
-        return db.run(r.table('devices').insert({
-          serial: serial
-        , provider: status.provider
-        , status: status.status
-        , statusChangedAt: r.now()
-        , createdAt: r.now()
-        }))
-      }
-      return stats
+}
+
+dbapi.saveDeviceStatus = function(serial, status) {
+  return dbapi.ensureDeviceSaved(serial)
+    .then(function() {
+      return db.run(r.table('devices').get(serial).update({
+        status: status
+      , statusChangedAt: r.now()
+      }))
     })
 }
 
+dbapi.setDeviceAbsent = function(serial) {
+  return db.run(r.table('devices').get(serial).update({
+    present: false
+  }))
+}
+
 dbapi.saveDeviceIdentity = function(serial, identity) {
   return db.run(r.table('devices').get(serial).update({
     platform: identity.platform