Reverse port forwarding works, but changes don't apply to new devices yet.

lib/db/api.js

@@ -22,6 +22,7 @@ dbapi.saveUserAfterLogin = function(user) {
         , group: wireutil.makePrivateChannel()
         , lastLoggedInAt: r.now()
         , createdAt: r.now()
+        , forwards: []
         }))
       }
       return stats
@@ -32,6 +33,20 @@ dbapi.loadUser = function(email) {
   return db.run(r.table('users').get(email))
 }
 
+dbapi.addUserForward = function(email, forward) {
+  return db.run(r.table('users').get(email).update({
+    forwards: r.row('forwards').default([]).append(forward)
+  }))
+}
+
+dbapi.removeUserForward = function(email, devicePort) {
+  return db.run(r.table('users').get(email).update({
+    forwards: r.row('forwards').default([]).filter(function(forward) {
+      return forward('devicePort').eq(devicePort)
+    })
+  }))
+}
+
 dbapi.loadGroup = function(email) {
   return db.run(r.table('devices').getAll(email, {
     index: 'owner'