Set policy_default default to 'allow'
Set policy_default default to 'allow'

This change is required in order to fix the default value of
allow_unconfigured in action-policy when no policy file is found
(choria-plugins/action-policy#5).

Since this module does not provide a policy by default, it would break
when choria-plugins/action-policy#4 is merged.

choria-io/mcollective-choria