Bug 1093931 - Update Loop mocha unit test framework to v2.0.1, which supports Promises, r=Standard8

--HG--
rename : browser/components/loop/test/shared/vendor/mocha-1.17.1.css => browser/components/loop/test/shared/vendor/mocha-2.0.1.css
rename : browser/components/loop/test/shared/vendor/mocha-1.17.1.js => browser/components/loop/test/shared/vendor/mocha-2.0.1.js