Add Puppet 6.x support

[bastelfreak]

Pull Request (PR) description

This Pull Request (PR) fixes the following issues

[bastelfreak]

So I accept (and expected) that puppet 6 fails because the yumrepo resource got pulled out:
https://travis-ci.org/voxpupuli/puppet-zabbix/jobs/430699716#L900

But I cannot reproduce this locally. I need to investigate this later.

[bastelfreak]

Okay I can now reproduce this. I tried to execute the tests with:

bundle exec rake spec_prep
bundle exec rspec spec/classes/agent_spec.rb

And puppet 6 is installed:

$ bundle list puppet
/home/bastelfreak/modulesync_config/modules/puppet-zabbix/.vendor/ruby/2.5.0/gems/puppet-6.0.0

But via my package manager I pulled in puppet 5:

$ pacman -Qi puppet
Name            : puppet
Version         : 5.5.3-1
Description     : Server automation framework and application
Architecture    : any
URL             : https://puppet.com/products/open-source-projects
Licenses        : Apache
Groups          : None
Provides        : None
Depends On      : facter  hiera
Optional Deps   : ruby-shadow: user password management
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 6.96 MiB
Packager        : Christian Rebischke <[email protected]>
Build Date      : Wed 18 Jul 2018 08:49:30 PM CEST
Install Date    : Wed 19 Sep 2018 09:56:56 AM CEST
Install Reason  : Explicitly installed
Install Script  : Yes
Validated By    : Signature

Deinstalling/updating my local puppet 5 package to puppet 6 allows me to reproduce the issue. I somehow expected a better environment isolation from bundler. I thought one of the primary usecases of bundler is the isolation between project-gems and systemwide-gems. @binford2k I can now confirm that this module fails on puppet 6 because of the yumrepo resource type missing in puppet core.

[bastelfreak]

Adding https://github.com/puppetlabs/puppetlabs-yumrepo_core to the .fixtures.yml works fine, but some other required types are also missing. Our selinux module needs the https://forge.puppet.com/puppetlabs/selinux_core as a dependency

[bastelfreak]

This depends at least on voxpupuli/puppet-selinux#271

[erosastyro]

Maybe use 6.1.0 instead of 7.0.0.