Create a mechanism for deleting temporary Obs and archived form data when form data is successfully processed at EMR side

Whenever temporary Obs are saved in mUzima, there's no mechanism to retire/delete the Obs when form data is successfully processed at the EMR. In addition, there is no way to compare Observations synced from server-side to tell whether they are the same ones saved as temporary on the device. The problem with this setup is that there might be duplicate sets of observations for the same encounter, one set being saved as temporary on the mobile device and the other set coming from server-side after sync. 

A proposed remedy to this problem is to send form data UUIDs alongside payloads that get submitted for processing and use them to track the status of the form data. During periodic sync, the app can ping the EMR to find out whether the form data has been processed. Whenever the app confirms that form data has been processed, it should delete the temporary encounters, observations and archived form data, and then sync processed observations and encounters from the EMR-side.