Move marketing emails away from Mailchimp

[KimberleyCook]

Description of the issue 📄

Currently we use Mailchimp for our marketing emails (transactional emails like workshop invites are sent via Sendgrid). This has become very expensive and we have found an alternative - Flodesk.

This task is to update the embedded newsletter sign up form as well as the API integration when people sign up for marketing emails to use Flodesk.

Screenshots 📷

Steps to fix 🛠

People can sign up to or manage marketing emails three ways on the websites:

• Sign up form at the bottom of the homepage and chapter pages (Fig. 1)
• During the account creation process they are prompted to sign up to the newsletter (Fig. 2)
• They can manage their subscription on the /subscriptions page (Fig. 3)

We use the gibbon gem to integrate with the Mailchimp API. AFAIK Flodesk doesn't have a Ruby wrapper for their API so we'll have to write our own. We'll only really need to support two features:

• Sign up to a general list via the account creation flow and on the /subscriptions page
• Opt-out of the newsletter (unsubscribe from the general list) on the /subscriptions page

Flodesk does support embedded forms so the current Mailchimp for will be easy to replace on the bottom of the homepage and chapter pages.

Migration plan

TBD, we'll have to come up with a migration plan to ensure no outage while we switch over from Mailchimp to Flodesk. AKA go live plan.

To do 📋

• Claim this issue (comment below, or assign yourself if you are part of the codebar org)
• Fork and clone the repository
• Update the relevant files. Follow the steps to fix section in this issue.
• Commit your changes as one commit. Use the title of this issue as your commit message
• Submit a pull request
• Mention this issue in the PR description by including it's number
• Have your pull request reviewed & merged by a codebar team member