Remove invalid characters from manifest

bbb-screenshare/webrtc-extensions/chrome/manifest.json

-/**
- * BigBlueButton open source conferencing system - http://www.bigbluebutton.org/
- *
- * Copyright (c) 2012 BigBlueButton Inc. and by respective authors (see below).
- *
- * This program is free software; you can redistribute it and/or modify it under the
- * terms of the GNU Lesser General Public License as published by the Free Software
- * Foundation; either version 3.0 of the License, or (at your option) any later
- * version.
- *
- * BigBlueButton is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
- * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License along
- * with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
- *
- */
-
 {
   "manifest_version": 2,
   "name": "screenshare test extension",