Fix: Let Orgas change FS roles again

Part of #747 (closed)

What does this MR do?

As discussed here: https://yunity.slack.com/archives/C74JC2V26/p1579113131077500

This MR (re-)enbables Orgas to change other user's roles.

How confident are you it won't break things if deployed?

Should be fine

Links to related issues

Any relevant links (issues, documentation, slack discussions).

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as Orga
3. Open another Foodsaver's / Bieb's / Bot's profile
4. Edit profile, change role, save
5. Do you get a green message? Has role been changed successfully?

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings