Students get an email when they are promoted from the waitlist

This will happen if an event's size increases, or another
student cancels.
Fix intermittent errors for redirect

Add assertion of header before checking URL redirect

Fixes: https://www.pivotaltracker.com/story/show/49712465
Job details hint string discusses a wider range of jobs
Merge pull request #161 from eanakashima/master

Le'ts have the "what's your job" example string describe more jobs.
Merge pull request #162 from faun/fix_intermittent_failures

Fix intermittent errors for redirect
updated meetup message to SF Ruby