* using browsersync instead of livereload
* `gulp serve` works as before
* `gulp sync` starts browserSync and serves UI on port 3000
* everything is built in `build/`
* build release with `gulp build --release`
- Also added linter configuration, and make linter fail on error
- fixing ES6 errors and added ES6 transformer
- gulp target to try local build
- linted gulpfile
- cant hook into gulp lint yet, because gulp does currently not support
ES6 which some rules demand, since gulp cant transpile itself, we have a
chicken and egg problem.
- ES6 transpiler for test runner
- removed old linter config
- adapted editorconfig to reflect linter config
