Install and configure pywikibot

Summary:
This is a follow-up for 1e344c0b.

Install the downloaded pywikibot as a package through setup.py,
so every Python 3 script can do an import pywikibot.

Provide configuration for DæghrefnBot.

Ref T1309

Test Plan: Run create_givenname or create_surname

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1309

Differential Revision: https://devcentral.nasqueron.org/D1218