(PDB-905) Fix containment-path for skipped events

We had removed some < v4 reporting code as part of the last release, but I had
also accidentally removed containment-path for skipped events. This was an
effort to drop older Puppet support basically.

This patch fixes that problem, and fixes the tests.

I've also cleaned up a couple of other typos and style items, plus
removed one more case of < v4 report format checking.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #1099 from kbarber/ticket/stable/pdb-905-null-containing-class-containing-path

(PDB-905) Fix containment-path for skipped events