introducing the foreman ext_pillar module
Cleanup for #13160

This commit makes the changes from #13160 conform to the Salt way by
kreturning booleans for enable/disable. In addition, it makes the
following changes:

1. Adds versionadded directives

2. Fixes leaked file handles by using with statements (and
   salt.utils.fopen).

3. Raises a CommandExecutionError in ares where the failure of a
   function reaches an error case.
Json is not going through serializers anymore. Refs #13158
correct erroneous os.kill() statement
add missing reference to error message
Added an execution module for varnish (https://www.varnish-software.com/)
fixed trailing whitespaces and stuff pylint complained about.
Merge pull request #7 from mfournier/os.kill-fix

fix mistake mentioned in #13162
Merge pull request #13161 from s0undt3ch/develop

Json is not going through serializers anymore. Refs #13158
Merge pull request #13164 from mortis1337/varnish-execution-module

Added an execution module for varnish
Lint
Merge branch 'puppet-housekeeping' of https://github.com/terminalmage/salt into terminalmage-puppet-housekeeping

Conflicts:
	salt/modules/puppet.py
Merge branch 'terminalmage-puppet-housekeeping' into develop
Merge pull request #13157 from bechtoldt/foreman_pillar

implementing a foreman ext_pillar module
move conditionsl logic and remove parens per lint #13157
Merge pull request #13165 from nicksloan/absolute_known_hosts

Allow arbitrary absolute path. Error on relative path without user argument.
don't import stdlib funcs into state modules
Add new postfix module
lint
Adding a very simple function to write provided contents to a file, overwriting existing contents.