Release candidate M4

Feature/terraform 0.12 sync develop (#103)

Sync develop branch to tf 0.12 branch

* Fix misleading variable description (#86)

* changed the description for the variable `enable_manage_gitlab_token`, since the second part of the description was misleading

* rewritten the description of the variable `enable_manage_gitlab_token` based on feedback from PR

* update changelog

* ci script update (#90)

* ci/bin/autodocs.sh: exit if dependencies are not installed
(pandoc or terraform-docs)

* ci/bin/verify-examples: make check for examples working
and not print some obscure error messages

* Adding docker pull policy Parameter (#89)

* adding pull policy parameter

* update documentation from master

* runautodocs

* regenerate README

* adding paramter to allow specify docker-machine ami

this allows us to also use the latest ubuntu 18.04
for the docker-machine instances

* adding paramter to allow specify docker-machine ami (#88)

this allows us to also use the latest ubuntu 18.04
for the docker-machine instances

* Update docs

* Release 3.6.0

* fix: availability zone in AWS region (#93)

* fix: availability zone in AWS region

* fix: use data source to determine az

* fix: use a variable to determine timezone (#94)

* fix: use a variable to determine timezone

* fix: update documentation

* Fix broken public example

* Move cache to moudle (#96)

FIx #91

* Release 3.7.0

* Add variable docker_machine_role_json allowing role policy customization (#100)

* Add variable docker_machine_role_json allowing role policy customization

* Update docs

* Add variable docker_machine_ssh_cidr_blocks allowing ssh ingress restriction (#101)

* Update names for docker machine security-rules (#102)

* Fix merge mistake

* Fix merge mistake