Update FSF address and GPLv2 text

Use GPLv2 text from http://www.gnu.org/licenses/gpl-2.0.txt and update
FSF address. Based on a patch by Shakthi Kannan
<shakthimaan@fedoraproject.org>.
Merge pull request #29 from tyll/fsf-address

Update FSF address and GPLv2 text