Form versioning and uuids

[janatalab]

For each form, create a uuid based on the rendered form, along with response options so that one can verify that responses on a form are being analyzed for the same form. Whenever a form is modified, a new uuid is generated. The editor only shows the most recent version of forms, but an option is provided to revert to an older version.

Same logic should be applied to questions. In fact, when constructing the form uuid, string together the question uuids.