(BCN, Due: 2015-02-01) Estimate number of mentors needed. 53

Problem/Motivation

Follow-up to #2232047: [META] Get ready for DrupalCon
Can be done really early, as soon as the DA has an estimate of attendees, mentors can be estimated as a percentage.
Should be done around 240 days in advance.

In the mentoring irc channel, ask the bot: docs?
which should have a list of docs, one is: sprint attendance?

For Barcelona, estimate is 53 mentors.

Proposed resolution

Remaining tasks