v1.3.1

Added

• Babel for JS transpiling ES6.

Removed

• gulp-uglify replaced with webpack uglify plugin.
• Unused jasmine-spec-reporter, jasmine-reporters, gulp-clean,
  gulp-coveralls, and browser-sync.
• Unused timer and isAnimating variables from ExpandableTransition.
• Refactored to remove gulp-load-plugins.
• Refactored to remove mocha-jsdom.

Changed

• Updated gulp file structure to match cfgov-refresh.
• Updated lint gulp task to support auto-fixing.
• Fixed codebase linter errors.
• Updated JS syntax to ES6.
• webpack, webpack-stream, chai, require-dir,
  and sinon to latest.
• dom-class-list toggleClass method had unnecessary apply method.