serialized upload to for better tracking of progress

apigee_mirror/components/opdk-upload-install-apigee-mirror.yml

diff --git a/apigee_mirror/components/opdk-upload-install-apigee-mirror.yml b/apigee_mirror/components/opdk-upload-install-apigee-mirror.yml
index 6fd1cc8..a177fd1 100644
--- a/apigee_mirror/components/opdk-upload-install-apigee-mirror.yml
+++ b/apigee_mirror/components/opdk-upload-install-apigee-mirror.yml
@@ -1,5 +1,6 @@
 ---
 - hosts: '{{ hosts }}'
+  serial: 1
   vars_files:
   - ~/.apigee/credentials.yml
   roles: