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.