Enable unit tests for ArcanistJscsLinterTestCase
Summary:
https://github.com/mdevils/node-jscs/issues/444 has been resolved in commit 0de667bac2491ba04d930ff94e990965213ba36b, which means that jscs can be easily run on files with any extension.
NOTE: JSCS version 1.5.7 is required.
Test Plan: arc unit
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley, Blessed Reviewers
Subscribers: epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D9789