Replace the old (and broken) jshint + jscsrc by eslint and configure
it to support some of the ES6 features.
The command `eslint` currently has one error which is a bug that was
discovered by its static analysis and should be fixed (usage of a
dead object).
This commit also introduces a new CSSEvents object that is used to
abstract vendor specifics events related to CSS transitions and
animations.
Fixes#183.
Fixes#179.
