Capture timings of requests

See discussion in #26 .

It would be nice to register some hooks with flask `before_request` and `after_request` that register timing information about the request:

`before_request`:
* request ID (likely using [`uuid.uuid4`](https://docs.python.org/3/library/uuid.html))
* start time
* Take into consideration time-zones etc...
* url for request (difference between endpoint, and parameters)
* number of samples being requested (maybe not applicable everywhere)
* API version

`after_request`:
* end time
* timing considerations should be the same
* maybe some job information, such as number of samples, that is not known until complete

See [this helpful SO post](https://stackoverflow.com/questions/10434599/get-the-data-received-in-a-flask-request) for a quick overview on the `flask.request` module, which should provide a lot of utilities for getting the above information.

Also see the [`flask.Request` docs](https://flask.palletsprojects.com/en/1.1.x/api/#flask.Request).

Start by reading discussion #26 and the Flask before_request, after_request, and Request documentation linked in the issue. Identify the application's request-handling entry points, then define how request IDs, timestamps, URLs, API versions, sample counts, and completion data are recorded; the work is done when the agreed timing information is captured consistently.

Written by the indexing model from the issue text.