Encrypt device name on account create, on first launch if needed

libtextsecure/storage/user.js

@@ -31,5 +31,13 @@
     getDeviceName() {
       return textsecure.storage.get('device_name');
     },
+
+    setDeviceNameEncrypted() {
+      return textsecure.storage.put('deviceNameEncrypted', true);
+    },
+
+    getDeviceNameEncrypted() {
+      return textsecure.storage.get('deviceNameEncrypted');
+    },
   };
 })();