Validate for required fields before enabling a data provider, Fixes T327

Summary:
  - Use the rules fields on the form field to validate for required fields

Test Plan:
  - Go to messages/settings
  - Attempt to enable a data provider with required fields that haven't been configured.
  - See an alertify show saying the data provider hasn't been configured and it should fail to get it configured.

Reviewers: rjmackay, shadowhand

Reviewed By: rjmackay, shadowhand

Subscribers: srutto, lkamau

Maniphest Tasks: T327

Differential Revision: https://phabricator.ushahidi.com/D301