Remove minion migrations entirely, refs T235

Test Plan:
```
git submodule sync
```

Reviewers: eyedol, rjmackay

Reviewed By: rjmackay

Subscribers: PapaLee, lkamau, dkobia, srutto, bodacea

Maniphest Tasks: T235

Differential Revision: https://phabricator.ushahidi.com/D264