credentials_updated for sw-client
credentials_updated for sw-client

Implement sw_client_service_credentials_updated in sw-client-service.c so
bisho can use this mechanism to inform libsocialweb while the user is
changed.

Signed-off-by: Gary Lin <a057d4b27e9e9055b973f54b519db54c22ed5ee8@novell.com>

GNOME/libsocialweb,GNOME/libsocialweb,ThomasBollmeier/libsocialweb-flickr-oauth,ThomasBollmeier/libsocialweb-flickr-oauth,lcp/libsocialweb,lcp/libsocialweb,ThomasBollmeier/libsocialweb-flickr-oauth,lcp/libsocialweb,GNOME/libsocialweb