GPG-KEY: Add our gpg key to the git repository

To import the key, do this:

  $ git show GPG-KEY | gpg --import

For more information, see pages 140-141 of Pro Git (Chacon)
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

iEYEABECAAYFAk3AxZwACgkQA2jvV5x7o7bDEwCgoNfMLPGYEvzgAZISskAutz7S
Wn0AoJdgh8pw6nU3U3kaSoEcvUWsxY4O
=mHMp
-----END PGP SIGNATURE-----
