(maint) Report errs correctly on settings apply

 - Previously when the `settings` catalog was built, it was possible
   for a `transaction` to fail, but not generate any useful failure
   information in `report.log` -- resulting in a message to the user of
   "Got 0 failure(s) while initializing:"
 - Furthermore, the `any_failed?` check against a `transaction` checks
   against the `resource_statuses` of the `transaction`, but the code
   to surface the error was looking in the `report.log`, which was a
   source of confusion
 - This commit examines `event` objects inside of `resource_statuses`
   for those with a `status` of `failure`, and uses them to report off
   of instead - resulting in clear error messages
- Additionally, some minor corresponding doc changes were made

Paired-with: Andrew Parker <andy@puppetlabs.com>
Merge branch 'settings-reporting'

* settings-reporting:
  (maint) Report errs correctly on settings apply