Update Analytics Tracking Invironment

[dakkad]

Update production environment to include Google Analytics property tracking ID: UA-124404404-1

[ithinkihaveacat]

That ID does seem to be the default, however it's not being output on https://ampbench.appspot.com/--perhaps because the GTAG_ID environment variable is not been defined in that environment?

@pietergreyling How is this supposed to work in production? Should the GTAG_ID be configured in app.yaml? (I'm not sure how this ever worked!)

[pietergreyling]

@ithinkihaveacat Yes, this issue is to have tracking ID implemented in the environment as per here:
https://cloud.google.com/appengine/docs/flexible/nodejs/integrating-with-analytics

[pietergreyling]

@ithinkihaveacat
I am not sure that building Google Analytics into an open source project like AMPBench is appropriate (?)

Out if principle I have opened an issue to have the GA code removed:
#100

However, I think we should all discuss this and agree on the best way forward.