Remove organization from superuser edit/index of users

[cielf]

Summary

You currently have to add an organization if you edit a user as a superuser. We don't need the link to the organization on the user at all anymore -- it's handled through the user's roles.

Why fix?

Outdated. This is not a high priority item, as it the function it is on is very rarely used.

Details

Note: Although this is ranked beginner, it does need some familiarity with the system. Please don't take this as your first issue.

Now that we have roles, users are no longer tied to organizations directly. The organization field can, therefore, be removed from the user entirely.

User in the superadmin interface is affected by this

Edit.
Remove the user-level organization from this view.

Index.
The organization column was good information to have for the organizations that have it -- can we list the organizations and partners that the user belongs to, through their roles, here instead? Rename the column "Banks and Partners"

New: Analagous changes to new are being handled with a different issue.

Sanity check.
We're pretty sure that's the only remaining place that User.organization is used. However, please do check. (If we're wrong, existing tests should fail, we hope.)

Criteria for completion

• functionality as described
• tests added and/ or modified to support the new functionality
• tests work!
• Please include screenshots in your PR

[cancelei]

I can take this one!