Setup dev environment

1. install nodejs
2. npm install
3. grunt to dev, any change to src/rule, src/template will regenerate proxy.pac under directory dist.
4. grunt deploy to generate new pac file and deploy it onto github.

rule files

1. Line beginning with # is comment.
2. .r file is rule file, HOSTS section means block the whole host; URLS section to block specify url, of course which is regex.
3. .m file is module file, which is planned to use define what rules included into build. But now we don't use it.