Apply linter fixes

Summary: Apply various linter fixes.

Test Plan: Eyeballed it.

Reviewers: chad, epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9449
Modernize `.arcconfig`.

Summary: There have been several changes to the `.arcconfig` file format since this repository was last updated. In addition, the `PhutilLintEngine` no longer exists.

Test Plan: Eyeball it.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9445