remove TA data
migration for admin emails
renamed GdiMailer to TeachingAssistantMailer
renamed GdiMailer to TeachingAssistantMailer
remove skylight
migration
admin mailer with a new TA message
link to the email system
Merge pull request #84 from feministy/admin_emails

Admins emailed when new TAs sign up; renamed GdiMailer to TeachingAssistantMailer