Merge pull request #7398 from s0undt3ch/0.17

[0.17 cherry-pick] single .pylintrc & travis code lint checks
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.