Support real-time metrics for google analytics

[Ameobea]

It would be awesome if the Google Analytics module supported real-time metrics along with aggregate traffic metrics on a monthly timeframe. The realtime API is apparently still in a beta (although it looks to have been that way since like 2015), but I was added in less than a couple hours immediately after filling in a Google Form.

Personally, I feel that viewing what's happening on my websites right now is a very valuable tool for the dashboard. It's a much more dynamic view and perfectly suits the dashboard format. I've got a very rough working implementation on my local fork, and I'll be working on cleaning it up and creating a pull request with these changes soon.