[3:3] Require that update_diaper_partner is successful before advancing to pending status

[armahillo]

(Pulled from RfG#671 )
Note - This requires work on both the diaper and partner apps. Each point below will require altering the api endpoint on each app as well as whatever is making the request to the endpoint.

Summary

In the Diaper app in the partner.rb model there is a method update_diaper_partner that immediately sets the partner status to pending regardless if the DiaperPartnerClient.post(attributes) was successful or not. We need to ensure that the post action was successful and then set the partner status to pending. We may need to schedule a retry on a fail or something similar.

Criteria for Completion

• A passing test that confirms that the status is NOT set if the post fails
• A passing test that confirms the status is set if the post is successful

Reference / History

This was originally part of #636, and is related to #1