Merge pull request #378 from pulp/mhrivnak-faq

adding a FAQ to the user guide that addresses checksum in unit key
adding 2.2.1 release notes
adding two more bug reports
Merge pull request #393 from pulp/mhrivnak-release-notes

adding 2.2.1 release notes
Merge pulp-2.2 => pulp-2.3, pre-build
Automatic commit of package [pulp-rpm] release [2.2.1-1].
Merge (-s ours) pulp-2.2 => pulp-2.3, post-build
Merge commit '558f67b2dc22a6ed203f8a8f4c5a3ffc2df7bd1b'
Merge branch 'pulp-2.3', post 2.2 build.