fix(package): update chokidar to version 2.0.0

Author: greenkeeper[bot]

package.json

@@ -19,7 +19,7 @@
     "url": "https://github.com/pvdlg/karma-postcss-preprocessor/issues"
   },
   "dependencies": {
-    "chokidar": "^1.7.0",
+    "chokidar": "^2.0.0",
     "lodash": "^4.17.4",
     "minimatch": "^3.0.4",
     "nodeify": "^1.0.1",