(#22431) Re-enable windows executable external facts

This reverts the change made in fe5e639fd8, as starting with facter
1.7.3, external executable facts are supported on Windows.

Also added words to ensure the facts.d should only be writable by
Administrators, otherwise, a non-Admin could escalate privileges.
Merge pull request #208 from joshcooper/support_windows_external_executable_facts

(#22431) Re-enable windows executable external facts
added info on OpenSSL to address Jira ticket. PE-1458
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lookupvar for empty variable returns nil not undefined

As per Andy Parker's work, `lookupvar` in custom functions and
`scope.lookupvar` in a template will now return `nil` not `:undefined`
when a fact or variable has no value.
Fix missing quotes in yaml frontmatter for three files
Add 3.3.0-rc3 release notes
Update node definitions page for changes in Puppet 3.3.0
Update references for 3.3.0-rc3
Merge remote-tracking branch 'upstream/master'
(#21133) Add versionable feature to windows package provider

Previously, the windows package provider knew what versions of
packages (MSI and exe) were installed, but did not report them,
e.g. when running puppet resource package.

The package provider is now versionable, and docs are updated accordingly with caveats.

https://github.com/puppetlabs/puppet/pull/1871
Merge pull request #209 from zacharyalexstern/master

lookupvar for empty variable returns nil not undefined
Guts: Override in-page TOC for type reference

That TOC was literally about six screens long. On a big monitor. Blow it away
and make a smaller multi-columned one, so you can see the start of the page from
the get-go! This isn't the most sustainable way to do this, but it at least
solves the worst of the fugly.
Revise preamble text of type reference to be more useful for beginners

- Cover the basics
- Link to language reference
Update 3.3.0-rc3 type reference w/ recent changes to generator
Clarify further about testing for undefined variables with lookupvar et al
Final 3.3.0 release notes
Merge 3.x "what's new" with release notes

These two shouldn't be separate pages, so... merge 'em.
Point puppet 3 sidebar at 3.stable references
Generate 3.3.0 references, delete 3.3.0-rc3 references
Swap an ad in the sidebar