Add staging repos

Also disable testing repos by default
Signed-off-by: Allan McRae <allan@archlinux.org>

conf/abs.conf

@@ -28,5 +28,5 @@ MIRRORLIST="/etc/pacman.d/mirrorlist"
 # Note: If a repo is removed, it is still fetched!
 # Repos must be preceded with a ! to prevent fetching
 #
-REPOS=(testing core extra community-testing community multilib)
+REPOS=(core extra community multilib !testing !community-testing !multilib-testing !staging !community-staging)