Squashed commits:
[45c2237] Add a `subscription-form-switch-to-student` event
[1ad9b8f] change experiment name, and re-enable switch-to-student workflow
[f7cdb78] Remove debug
[4b9778a] Incorporate collaborator alternative plans
[701e80b] Add collaborator plans for heron and ibis
[287aa0f] AB test plans from editor page
[c74052e] Fix change-plan view for default plans
[1a947d6] Use correct plan codes
[1eecda7] Adjust prices
[69c4c7b] Introduce two plans
[8b8d5f8] Rename sixpack experiment
[c332002] Fix up the change-plan page
[c7af52d] Overhaul change-plan page, show only plans from current generation
[33d86bf] update plan
[5bbd946] Add a basic plans AB test
This prevents a crash later when we refer to properties
of the plan object, which can end up being `null` when
the `planCode` is either missing, or not a valid code.
- always show the manage button if you are the group owne
- only show the recurly subscription part if you are the subscription owner
- always try and loop through groups you can leave
- get all accounts does get all of them by looping through all pages
- creating coupons requires which plan the coupon is for
- fixed the total price shown to people so it includes tax
