fsutils -> Typescript (#978)

* typescript fsutils, fix coverage reporting

* use default parameter in listfiles

package.json

@@ -49,6 +49,18 @@
     "url": "https://github.com/firebase/firebase-tools/issues"
   },
   "homepage": "https://github.com/firebase/firebase-tools",
+  "nyc": {
+    "require": [
+      "ts-node/register"
+    ],
+    "extension": [
+      ".js",
+      ".ts"
+    ],
+    "exclude": [
+      "src/test/**/*"
+    ]
+  },
   "dependencies": {
     "JSONStream": "^1.2.1",
     "archiver": "^2.1.1",
@@ -110,6 +122,7 @@
     "prettier": "1.14.3",
     "sinon": "^6.3.4",
     "sinon-chai": "^3.2.0",
+    "source-map-support": "^0.5.9",
     "ts-node": "^7.0.1",
     "tslint": "^5.11.0",
     "tslint-plugin-prettier": "^2.0.0",