Refactor Candidates for version = v0.3.1

[ydennisy]

There are many small refactor tasks which need to be complete before release of v0.3.0

• remove console.log() on production (server)
• remove console.log() on production (client)
• improve setup in app.yaml
• update nodejs runtime to 10 on local and GAE
• log the version and environment on client on startup
• improve the process.env usage for various environments
• remove static / hardcoded URLs
• serve static files (dist) from a CDN
• update cookies lib to use https://github.com/js-cookie/js-cookie as in gtm module