VNC authentication works, although there is no UI for adding passwords

yet. Direct database manipulation is required for now.

lib/db/api.js

@@ -100,6 +100,27 @@ dbapi.lookupUserByAdbFingerprint = function(fingerprint) {
     })
 }
 
+dbapi.lookupUserByVncAuthResponse = function(response, serial) {
+  return db.run(r.table('vncauth').getAll([response, serial], {
+      index: 'responsePerDevice'
+    })
+    .eqJoin('userId', r.table('users'))('right')
+    .pluck('email', 'name', 'group'))
+    .then(function(cursor) {
+      return cursor.toArray()
+    })
+    .then(function(groups) {
+      switch (groups.length) {
+        case 1:
+          return groups[0]
+        case 0:
+          return null
+        default:
+          throw new Error('Found multiple users with the same VNC response')
+      }
+    })
+}
+
 dbapi.loadGroup = function(email) {
   return db.run(r.table('devices').getAll(email, {
     index: 'owner'