Register heat image in sahara image registry for fake plugin

Fake plugin can work with heat image. Even more, sahara uses heat
to provision instances. So, registering image in sahara image
registry.

Change-Id: Ie498fc05d0afe7f276b6f29f20a61abb58a5c676
Closes-Bug: #1402856
diff --git a/extras.d/70-sahara.sh b/extras.d/70-sahara.sh
index 2a34999..f177766 100644
--- a/extras.d/70-sahara.sh
+++ b/extras.d/70-sahara.sh
@@ -15,6 +15,7 @@
         create_sahara_accounts
     elif [[ "$1" == "stack" && "$2" == "extra" ]]; then
         echo_summary "Initializing sahara"
+        sahara_register_images
         start_sahara
     fi