Make Arch Linux users install gevent from the official repository
Improve CWS login handler

Store the password in the cookie and make additional checks.

This should limit damage in case the secret_key is left at its default
value when ip_lock or block_hidden_users are on. It also allows admins
to forcefully logout a user by simply changing its password.
Optimize DB query for submission information.

Avoid n queries per submission to fetch submission result, token, files, etc,
by preloading them in the same query. Load time for a page with 1000
submissions goes from 30 seconds to about 1 second. Similar results with ES and
SS when they go to check on ALL THE SUBMISSIONS.
Improve performance of rankings page.