chore(package): update shelljs to version 0.8.4

Closes #11

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "nyc": "^12.0.1",
     "protractor": "^5.3.2",
     "rxjs": "^5.5.10",
-    "shelljs": "0.8.2",
+    "shelljs": "0.8.4",
     "simple-mapper": "^2.1.3",
     "sorcery": "^0.10.0",
     "source-map-support": "^0.5.6",