Delete package.json from template

This way the one generated by `init.js` doesn’t get overwritten later.
This fixes #149 which got broken as part of #94

template/package.json

-{
-  "name": "my-app",
-  "version": "0.0.1",
-  "private": true,
-  "devDependencies": {
-    "react-scripts": "0.1.0"
-  },
-  "dependencies": {
-    "react": "^15.2.1",
-    "react-dom": "^15.2.1"
-  },
-  "scripts": {
-    "start": "react-scripts start",
-    "build": "react-scripts build",
-    "eject": "react-scripts eject"
-  }
-}
\ No newline at end of file