Removed discover_ids.py
Removed discover_ids.py

This utility no longer works since Twitter have changed their API. Since
twarc really is a tool designed for working with the API this
functionality is not going to be supported going forward. I recommend
you take a look at either of these projects since they try to keep up to
date with all the changes Twitter make to their user interface.

* twint: https://github.com/twintproject/twint
* snscrape: https://github.com/JustAnotherArchivist/snscrape

closes #375

hugovk/twarc,DocNow/twarc