fix(package): update clean-css-cli to version 4.0.8

https://greenkeeper.io/
2017-02-22 16:31:24 +00:00 · 2017-02-22 16:31:24 +00:00 · aed334c320
--- a/package.json
+++ b/package.json
@ -9,7 +9,7 @@
  "dependencies": {
    "addons-linter": "0.15.15",
    "clean-css": "4.0.7",
-    "clean-css-cli": "4.0.7",
+    "clean-css-cli": "4.0.8",
    "less": "2.7.2",
    "stylus": "0.54.5",
    "uglify-js": "2.7.5"