chore(package): update mkdirp to version 1.0.4

Closes #45

Author: greenkeeper[bot]

package.json

@@ -87,7 +87,7 @@
     "karma-ie-launcher": "^1.0.0",
     "karma-qunit": "^3.1.1",
     "karma-safari-launcher": "^1.0.0",
-    "mkdirp": "^0.5.1",
+    "mkdirp": "^1.0.4",
     "node-sass": "^4.5.3",
     "node-static": "^0.7.10",
     "npm-run-all": "^4.1.2",