chore(package): update css-loader to version 0.28.7

Closes #656

package.json

@@ -42,7 +42,7 @@
     "chromedriver": "^2.31.0",
     "classnames": "2.2.5",
     "copy-webpack-plugin": "4.0.1",
-    "css-loader": "0.28.5",
+    "css-loader": "0.28.7",
     "enzyme": "^2.8.2",
     "eslint": "^4.4.1",
     "eslint-config-scratch": "^4.0.0",