Add new stack phase: post-extra

The current existing phases "post-config" and "extra" are not
sufficient to allow local.conf overrides to extra type services
because they run after the services are installed and configured.
This commit introduces a new phase called "post-extra" that runs
after these existing phases. With this change, users are able to
leverage local.conf to provide overridden options to services
like Tempest.

Change-Id: I5d758eebfda804dd1d8cbc3d5cc35ef4dcc8c96f
Closes-Bug: #1249085
diff --git a/extras.d/80-tempest.sh b/extras.d/80-tempest.sh
index 75b702c..0186e36 100644
--- a/extras.d/80-tempest.sh
+++ b/extras.d/80-tempest.sh
@@ -14,6 +14,9 @@
         echo_summary "Initializing Tempest"
         configure_tempest
         init_tempest
+    elif [[ "$1" == "stack" && "$2" == "post-extra" ]]; then
+        # local.conf Tempest option overrides
+        :
     fi
 
     if [[ "$1" == "unstack" ]]; then