Add some configuration keys

1. Add local gulp copy at `package.json` to get rid `Local gulp not found in current dir` error
2. Replace the deprecated `gulp-clean` with `gulp-rimraf`
3. Add some info (repo, bugs, homepage, keywords) in `package.json`
4. Add start script to `package.json`, hence we can do `npm start`
5. Livereload support (on chrome https://chrome.google.com/webstore/detail/livereload/jnihajbhpnppcggbcgedagnkighmdlei, please let the port 35729 free). Activate the server via `$ gulp watch`