gnome-keyring bracnhed for 2.18

[Nate Nielsen <nielsen-list memberwebs com>]

gnome-keyring has branched for 2.18.

Some goals for 2.20 (may not be completely met):

 * X.509 key storage in the form of a PKCS#11 module. This
   allows GNOME programs to store certificates and keys in
   a single location, protected by a single passphrase.
 * Use non-pageable memory for storing secrets and keys.

Cheers,
Nate Nielsen