Madmimi Email Integration

Create from the discussion around issue #296

Current status

Draft only, do not code yet without signoff from Dom+Eli

User story

As an administrator, I want people to be automatically subscribed to our mailing list provider, Madmimi, when people click the checkbox for 'send me updates about EventName'

Requirements

• Support multiple mailing list providers (i.e. Madamimi, mailchimp, etc)
• Support multiple mailing lists (i.e. main promo list, staff newsletter, etc)
• Daemonized support

Implementation thoughts:

New table/model called EmailSubscriptions