fix(grunt-purgecss): add all files for publishing
fix(grunt-purgecss): add all files for publishing

- remove main, module, directory and files from package.json
- add directory to the repository property
- fix types property to point to the right file

FullHuman/purgecss,FullHuman/purgecss,FullHuman/purgecss,FullHuman/purgecss