chore(package): update file-exists to version 5.0.0 (#2413)

package.json

@@ -22,7 +22,7 @@
     "clang-format": "1.0.55",
     "del": "~3.0.0",
     "eslint-plugin-angular": "~3.1.0",
-    "file-exists": "4.0.0",
+    "file-exists": "5.0.0",
     "google-closure-compiler": "~20170910.0.0",
     "gulp": "~3.9.1",
     "gulp-autoprefixer": "~4.0.0",