Remove unnecessary `css-parse` dependencies

  - Specifying same module in `dependencies` and `devDependencies` is meaningless
  - `peerDependencies` is only for plugging in

By this change, `npm install` will install `css-parse` as child of `grunt-combine-media-queries` only.

This closes #10.
Merge pull request #19 from hail2u/optimize-package.json

Remove unnecessary `css-parse` dependencies