molecule scenario to test upgrading from releases

Provide a separate scenario to install the last release, then update to
the current one.
Also includes improved deployment verification (check if uploading a
.txt through the API works).

ansible/molecule/default/converge.yml

@@ -1,7 +0,0 @@
----
-- name: Converge
-  hosts: all
-  tasks:
-    - name: "Include ansible"
-      include_role:
-        name: "ansible"