Don't make pkg/service states available unless provider module is loaded

This prevents ugly tracebacks when an OS does is not properly detected,
and no pkg or service provider was loaded for the minion. pkg and
service states will still fail, but they'll fail more gracefully,
without the traceback.
Merge pull request #7408 from terminalmage/docs

fix sphinx build warning due to invalid RST
Merge pull request #7405 from terminalmage/issue7371

Don't make pkg/service states available unless provider module is loaded
Fix `pep8` `E302` issue
Fix typo