Generate shasum checksum for artifacts.

Change-Id: I9992d65eefcd1f7d688aa734a1f676c67199bec4
diff --git a/jobs.yaml b/jobs.yaml
index 810fa8b..dc005eb 100644
--- a/jobs.yaml
+++ b/jobs.yaml
@@ -70,6 +70,7 @@
     builders:
       - shell: stdbuf -oL -eL mispipe "sudo ~mininet/mininet/util/vm/build.py -v --branch {branch} --test sanity {flavor} --chown `whoami`"  "tr '\r' ' '"
       - shell: zip `basename -s .ovf */*.ovf`.zip */*.vmdk */*.ovf
+      - shasum */*.vmdk */*.ovf */*.zip > `basename -s .ovf */*.ovf`.sha
     publishers:
       - archive:
             artifacts: '**'