Update README and package.json to use yarn instead of npm

Author: mzikherman

README.md

@@ -162,32 +162,32 @@ Our mutation type then creates the `introduceShip` field using the return value
 After cloning this repo, ensure dependencies are installed by running:
 
 ```sh
-npm install
+yarn install
 ```
 
 This library is written in ES6 and uses [Babel](http://babeljs.io/) for ES5 transpilation and [Flow](http://flowtype.org/) for type safety. Widely consumable JavaScript can be produced by running:
 
 ```sh
-npm run build
+yarn build
 ```
 
-Once `npm run build` has run, you may `import` or `require()` directly from node.
+Once `yarn build` has run, you may `import` or `require()` directly from node.
 
 After developing, the full test suite can be evaluated by running:
 
 ```sh
-npm test
+yarn test
 ```
 
 While actively developing, we recommend running
 
 ```sh
-npm run watch
+yarn watch
 ```
 
 in a terminal. This will watch the file system run lint, tests, and type checking automatically whenever you save a js file.
 
-To lint the JS files and run type interface checks run `npm run lint`.
+To lint the JS files and run type interface checks run `yarn lint`.
 
 ## License
 

package.json

@@ -28,7 +28,7 @@
   },
   "scripts": {
     "prepublish": "./resources/prepublish.sh",
-    "test": "npm run lint && npm run check && npm run testonly",
+    "test": "yarn lint && yarn check && yarn testonly",
     "testonly": "babel-node ./node_modules/.bin/_mocha $npm_package_options_mocha",
     "lint": "eslint src",
     "check": "flow check",