Fixtures and scripts to load MW database with a small set of test data for UMAPI.

Add seed.sql; do not drop tables and only create tables if they do not exist yet
Add edit_page_tracking table
Add fixtures for logging table
Add instructions on how to run mwdumper
Add Python script to import logging table data

Change-Id: I05daf93edcbbcdc3fa0ee42a6184e37623b4dd10
Merge "Fixtures and scripts to load MW database with a small set of test data for UMAPI."