Update to track latest plugin-css?

[mikol-styra]

package.json is currently pinned to plugin-css@0.1.30:

  "dependencies": {
    "less": "^2.7.1",
    "systemjs-plugin-css": "^0.1.30"
  },
  "jspm": {
    "dependencies": {
      "css": "github:systemjs/plugin-css@0.1.30"
    },

Dunno if that is intentional or not.