Update to latest versions of GPL-2.0 and LGPL-2.1

Pull copies of these files directly from the GNU website:
  http://www.gnu.org/licenses/gpl-2.0.txt
  http://www.gnu.org/licenses/lgpl-2.1.txt

Fixes the address of the Free Software Foundation (BZ #15844). Also
includes some minor formatting changes and corrects references to
the GNU "Library" General Public License.