[v2] Registration, account confirmation, password resets and email flows

[archived-m]

All of the account nitty gritty. For emails we need to use the node library for sendgrid for now, and use something like mailtrap for local development and testing.

[th0rgall]

I'm closing this since a v2 rewrite is currently not on the roadmap.

and use something like mailtrap for local development and testing.

In #293 I added logging for SendGrid calls, so that sent email content can be viewed in logs when a SendGrid API key is missing (intended for local development).

We could verify SendGrid Template IDs with Sandbox Mode, but for the rest, SendGrid doesn't offer local development testing solutions. Templates made in SendGrid can only be tested and sent via SendGrid.

Mailtrap offers an Inbox Email Address (which we would need to send SendGrid emails to), but only on their Business plan. That doesn't seem to be worth it. For now, developers can use their own regular test accounts.