test: modernize mocha config (#518)

Author: JustinBeckwith

packages/google-cloud-dialogflow/.mocharc.json

@@ -0,0 +1,5 @@
+{
+  "enable-source-maps": true,
+  "throw-deprecation": true,
+  "timeout": 10000
+}

packages/google-cloud-dialogflow/package.json

@@ -11,9 +11,7 @@
   "main": "src/index.js",
   "files": [
     "protos",
-    "src",
-    "AUTHORS",
-    "COPYING"
+    "src"
   ],
   "keywords": [
     "google apis client",
@@ -50,13 +48,11 @@
     "eslint-config-prettier": "^6.0.0",
     "eslint-plugin-node": "^11.0.0",
     "eslint-plugin-prettier": "^3.0.0",
-    "intelli-espower-loader": "^1.0.1",
     "jsdoc": "^3.6.3",
     "jsdoc-fresh": "^1.0.1",
     "jsdoc-region-tag": "^1.0.2",
     "linkinator": "^1.5.0",
     "mocha": "^7.0.0",
-    "power-assert": "^1.4.4",
     "prettier": "^1.7.4"
   }
 }