Improve the ODK sync to make it customizable so that other ODK, with different structured, can be easily mapped to DengueChat DB structure.

[sofiarivas93]

Steps:

1. Read the documentation and understand the current structure of ODK. Issue 840
2. Customize how the worker processes the form and create the UI so that an admin user can configure any ODK xml and map specific fields in a form to fields in a table of the database.