[storlets] Transition Stein to EM

This transition the stein branch to extended maintenance.
Changes for bugfixes and things the team deems important are
still encouraged, but there will no longer be official releases
off of the branch.

Please +1 if the team is ready for us to proceed with this
transition, or -1 if there are any final backports currently in
flight that we should wait for. For the latter case, please
update the patch with the new commit hash after doing a final
release to get those changes out so we know to proceed with the
transition.

Change-Id: I9a90ff0d802dcbac0999be4c203510c149b02dc5

deliverables/stein/storlets.yaml

@@ -23,6 +23,10 @@ releases:
       - repo: openstack/storlets
         hash: fce31c97f2d12e664b95f74b5ca6a66a13a0487a
     version: 3.0.0
+  - version: stein-em
+    projects:
+      - repo: openstack/storlets
+        hash: fce31c97f2d12e664b95f74b5ca6a66a13a0487a
 repository-settings:
   openstack/storlets: {}
 cycle-highlights: