Adds an .editorconfig and a task to check style via jsxcs

https://www.npmjs.org/package/jsxcs is a fork of https://www.npmjs.org/package/jscs which does not fail when checked source contains jsx syntax (React). JSCS will probably support JSX in the future.

Google's styleguide is used to verify the source code with the only exception that the line length can be 120 characters.