Send batch information with submission

[enketo-issue-mover]

From @MartijnR on April 28, 2016 19:23

The current OpenRosa Submission API for batches can be tricky to implement on the server side when submissions are split into batches.

Investigate adding 2 headers: X-OpenRosa-Batch-Total: .. and X-OpenRosa-Batch-Index: .. headers.

This wouldn't break anything for existing OpenRosa servers.

Copied from original issue: kobotoolbox/enketo-express#492

[enketo-issue-mover]

From @MartijnR on April 28, 2016 19:36

Seems feasible, less than 1 day of work.

Probably better to make these: X-Enketo-Batch-Total and X-Enketo-Batch-Index

[enketo-issue-mover]

From @MartijnR on May 9, 2016 22:13

Checked with ODK devs, just in case there is a desire to meet this requirement in ODK Collect as well: https://groups.google.com/forum/#!topic/opendatakit-developers/vsBlXvoa9Xk

[enketo-issue-mover]

From @MartijnR on May 16, 2016 19:7

If instead we could use the *incomplete* form data part as in ODK Collect, we wouldn't have to deviate.