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/commands/command.py

@@ -4,20 +4,11 @@
 # (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>, and others
 # (c) 2016, Toshio Kuratomi <tkuratomi@ansible.com>
 #
-# 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': ['stableinterface'],
@@ -92,11 +83,10 @@ EXAMPLES = '''
 
 import datetime
 import glob
-import shlex
 import os
+import shlex
 
 from ansible.module_utils.basic import AnsibleModule
-from ansible.module_utils.six import b
 
 
 def check_command(module, commandline):
@@ -190,14 +180,14 @@ def main():
     delta = endd - startd
 
     if out is None:
-        out = b('')
+        out = b''
     if err is None:
-        err = b('')
+        err = b''
 
     result = dict(
         cmd      = args,
-        stdout   = out.rstrip(b("\r\n")),
-        stderr   = err.rstrip(b("\r\n")),
+        stdout   = out.rstrip(b"\r\n"),
+        stderr   = err.rstrip(b"\r\n"),
         rc       = rc,
         start    = str(startd),
         end      = str(endd),