user provisioning is not compatible with ansible 2.1 security

[jaclu]

In order for this to run under ansible 2.1 you either have to create ansible.cfg with the following content (Strongly advised against in Ansible docs):

[defaults]
allow_world_readable_tmpfiles = True

What is more in line with ansible best practices is to run ansible as remote user root using pub-key auth, and don't bother with setting up the provisioning user on the target machine
This also makes the param --ask-become-pass obsolete.

1. add to vars/all.yml
   ansible_user: root

2. from ckan.yml, db.yml & solr.yml remove the line user: provisioning