Generate Index.html with webpack - Closes #514

[faival]

What was the problem?

• dev-ops requires to check built version deployed within the html of the application
• bundles at the moment do not contain hash strings (cached forever)
• automate injection of inline css on head of document

How did I fix it?

• added meta tag in head of document displaying current package.json version:
• bundles now append the hash used to generate them (only for production build)
• head css has been moved to a separate file, (now it's stylelinted, and fixed)

How to test it?

• verify head of document contains current version in package.json
  <meta data-lisk-hub-version="0.2.0-rc.1">
• verify scripts inclusion in body contain the hash in the referenced bundle

<link rel="stylesheet" href="./styles.c99be3303f67c17c6c39.css">
<script src="./bundle.vendor.c99be3303f67c17c6c39.js"></script>
<script src="./bundle.app.c99be3303f67c17c6c39.js"></script>

• verify there's a style tag in head containing the styles of src/assets/css/styles.head.css and those are minified

<style type="text/css">
          body{background-color:#013165}.splash-screen{
...
</style>

Review checklist

• The PR solves Generate index.html with webpack #514
• All new code is covered with unit tests
• All new features are covered with e2e tests
• All new code follows best practices

[slaweet]

Good job, Pablo

[faival]

dev build goal should also inject styles in head.

npm run dev has broken styles