Add a table with users names

Add a table with the names of the users which added
Wikipedia tags since the previous day.
Add option --download_redirects

Check which articles are redirects and create a list
data/wikipedia/redirects/redirects so that they can be
manually copied to non_mappable file.
Uncomment a command
Add more credits
Move the code about mappers to the new file users.py
Fix minor errors and typos
Print progress and skip if file does not exist
Fix errors reported by pyflakes