Create post-first night survey/email/checkin process

To try and be more proactive about new members, maybe we can create a process for checking in with new members.

Some ideas I had were:

- a very simple email to everyone who came that week using the flowdock email invite list.
- a survey that asks how their first night went so we can start to improve that experience.
- just having one of the Community Organizers checkin with folks on flowdock afterwards to see if they got into a project, if they need any introductions, or where they're at.

Start by comparing the three proposed approaches: emailing new members through the Flowdock email invite list, sending a first-night survey, or having Community Organizers check in on Flowdock. Define one concrete process, its owner, and how follow-up outcomes will be recorded; the issue does not name files, tests, or an implementation entry point.

Written by the indexing model from the issue text.