Change timeit to show hostname and be more discreet in visibility

We are doing DataDog stuff, which has us loading certain URLs in the browser and looking at load times. We've wanted to know which of the 3 app servers got the request, as well as a convenient server-side measurement of elapsed time.

Change the timeit middleware to let it always run, but:

- Inject itself above the copyright in a white font
- On hover, change to gray so you can see it
- Display the hostname and the elapsed time for the request