Allow paas-docker role to succeed when no config is provided

Summary:
Without any pillar config, some for loop makes the states fail,
as they expect at least one entry or the variable present.

Test Plan: salt-call --local state.apply roles/paas-docker @ docker-001

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2323