Capture artifacts from ical generation

It's difficult to verify that a change worked without being able to
check the .ical file.  Capture it and the index.html for later
inspection.

Change-Id: I9be1d6f71a0d0578f1f7e34106c483824cc0a707

.zuul.yaml

@@ -5,6 +5,8 @@
       Run tests using tox with the ``ical`` environment.
     vars:
       tox_envlist: ical
+      zuul_copy_output:
+          '{{ ansible_user_dir }}/output': 'logs'
 
 - project:
     check:
@@ -13,3 +15,8 @@
     gate:
       jobs:
         - irc-meetings-tox-ical
+
+
+- hosts:
+    roles:
+      - role: stage-output