docs(test-helpers): add short readme, vue as dep

Author: posva

packages/@posva/vuefire-test-helpers/README.md

@@ -2,6 +2,12 @@
 
 > helpers used for tests in packages of vuefire repo
 
+## Usage
+
+```js
+import utils from '@posva/vuefire-test-helpers'
+```
+
 ## License
 
 [MIT](http://opensource.org/licenses/MIT)

packages/@posva/vuefire-test-helpers/package.json

@@ -20,10 +20,10 @@
     "type": "git",
     "url": "git+https://github.com/vuejs/vuefire.git"
   },
-  "scripts": {
-    "test": "echo \"Error: run tests from root\" && exit 1"
-  },
   "bugs": {
     "url": "https://github.com/vuejs/vuefire/issues"
+  },
+  "dependencies": {
+    "vue": "^2.5.17"
   }
 }