Get rid of more wildcard imports and add boilerplate to more modules

This commit cleans up the following module categories:
* messaging
* inventory
* crypto
* commands
* clustering
* cloud/webfaction
* cloud/docker
* cloud/digital_ocean

lib/ansible/modules/cloud/docker/docker_volume.py

@@ -2,21 +2,12 @@
 # coding: utf-8
 #
 # Copyright 2017 Red Hat | Ansible, Alex Grönholm <alex.gronholm@nextday.fi>
-#
-# This file is part of Ansible
-#
-# Ansible is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# Ansible is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+
 ANSIBLE_METADATA = {'metadata_version': '1.0',
                     'status': ['preview'],
                     'supported_by': 'community'}
@@ -112,8 +103,8 @@ except ImportError:
     # missing docker-py handled in ansible.module_utils.docker
     pass
 
-from ansible.module_utils.six import iteritems, text_type
 from ansible.module_utils.docker_common import DockerBaseClass, AnsibleDockerClient
+from ansible.module_utils.six import iteritems, text_type
 
 
 class TaskParameters(DockerBaseClass):
@@ -258,5 +249,6 @@ def main():
     cm = DockerVolumeManager(client)
     client.module.exit_json(**cm.results)
 
+
 if __name__ == '__main__':
     main()