Add "Release Notes/Known Bugs" to Changelogdds "Release Notes/Known Bugs" to Changelog, updates file format to markdown, standardizes the format of previous entries

Per a request to have initial release notes that specifically listed known issues for this PE 3.2 release, and barred by time constraints from automating a pull from open issues in JIRA, this commit adds a Release Note and Known Bug section to the Changelog for the imminent 3.2 release. As it will display on the Forge, updates file type to markdown and standardizes previous entries.
Merge pull request #255 from laurenrother/1.4.x

Add "Release Notes/Known Bugs" to Changelog
Prepare metadata for supported module release.
Merge pull request #253 from apenney/add-metadata

Prepare metadata for supported module release.
Prepare supported module 1.4.2
Merge pull request #256 from apenney/supported-142

Prepare supported module 1.4.2
Add back in missing fields to work around Puppet bug.
Merge pull request #257 from apenney/last-minute-fix-metadata

Add back in missing fields to work around Puppet bug.
Fix typo.

Group was incorrectly spelt, but because the file was absent this
should have resulted in a noop in practice.
Merge pull request #267 from apenney/fix-typo

Fix typo
Fix typo in ppa.pp
Merge pull request #274 from fdrouet/fix_typo

Fix typo in ppa.pp
Pin Rake to 10.1.1 in Gemfile

The latest Rake update requires Ruby >= 1.9. This update
fixes the failing 1.8.7 tests by pinning Rake to the last
supported version on ruby 1.8.7.
Merge pull request #276 from blkperl/fix_rake

Pin Rake to 10.1.1 in Gemfile
backports: Allow setting a custom priority.

The module used to always pin backports to a priority of 200. This
default is still retained but is now configurable.

Additionally the default is now an Integer, not a 'quoted Integer' and
the tests have been updated to reflect this. This matters for future
parser as it will now kick people if they pass in a stringified integer
as priority.
Merge pull request #275 from daenney/backports-pin-priority

backports: Allow setting a custom priority.
unattended_upgrades: Fix matching security archive

The default configuration we were writing for Debian was only working
for Squeeze, from Wheezy and onwards this wasn't working anymore. This
has to do with the fact that we should now be using Origins-Pattern
according to the unattended-upgrades docs. However, Ubuntu didn't
entirely get with the program yet...

This change reflects the defaults that unattended-upgrade installs on
every platform we support. In order to do so the unattended-upgrades
Debian archive for Squeeze, Wheezy, Lucid, Precise and Trusty were
downloaded and the default /etc/apt/apt.conf.d/50unattended-upgrades
checked for its content with regard to using Allow-Origins or
Origins-Pattern.

Fixes #277
Merge pull request #278 from daenney/fix-unattended-upgrades

unattended_upgrades: Fix matching security archive
Small patch to fix the spacing that makes lint fail.
Merge pull request #279 from apenney/fix-spacing

Small patch to fix the spacing that makes lint fail.