(PDK-511) Add strict checking for PDK unit test templates

[da-ar]

Background: resource-api will check get values to see if they have been modified by canonicalize and will throw if Puppet strict is at :error level.

This change ensures that tests are run at the highest level by default.

[DavidS]

Amended with a bit of docs and a minor fixup.

[rodjek]

Will this create/expose errors in manifest tests that previously would have gone unnoticed? If so, it's probably best to wait on merging this until we get closer to 1.5.0.

[DavidS]

I ran pdk test unit --parallel with and without :error over all supported modules. all modules marked with a + in the list below are net-new failures when enabling that:

david@davids:~/git/modulesync_configs/modules$ diff -u failed.clean failed
--- failed.clean	2018-03-13 09:55:01.370863816 +0000
+++ failed	2018-03-13 08:53:19.746532309 +0000
@@ -1,7 +1,15 @@
 /home/david/git/modulesync_configs/modules/puppetlabs-apache
+/home/david/git/modulesync_configs/modules/puppetlabs-chocolatey
 /home/david/git/modulesync_configs/modules/puppetlabs-dsc
+/home/david/git/modulesync_configs/modules/puppetlabs-haproxy
+/home/david/git/modulesync_configs/modules/puppetlabs-ibm_installation_manager
 /home/david/git/modulesync_configs/modules/puppetlabs-ntp
 /home/david/git/modulesync_configs/modules/puppetlabs-powershell
 /home/david/git/modulesync_configs/modules/puppetlabs-puppet_agent
+/home/david/git/modulesync_configs/modules/puppetlabs-sqlserver
+/home/david/git/modulesync_configs/modules/puppetlabs-stdlib
+/home/david/git/modulesync_configs/modules/puppetlabs-tftp
 /home/david/git/modulesync_configs/modules/puppetlabs-vcsrepo
+/home/david/git/modulesync_configs/modules/puppetlabs-websphere_application_server
+/home/david/git/modulesync_configs/modules/puppetlabs-wsus_client
 /home/david/git/modulesync_configs/modules/yang_ietf
david@davids:~/git/modulesync_configs/modules$ 

We might want to change the default to :warning, which is puppet's default. That way the resource api can recommend turning it up, using the unmodified template, without impacting existing modules.

[bmjen]

+1 to defaulting to the default, and allowing customization to strict.

[da-ar]

Updated to use ":warning" as the default value. Additional description added to readme encouraging the stricter use of ":error"