Minor logging improvements. WIP medic/medic-webapp#714
fixed error logging message.
added debug mode example to readme.
fixed couple bugs in update_sent_forms WIP medic/medic-webapp#714

Don't call a save if nothing was changed, also use audit when saving.

We also don't need to run more than once on a form submission.
removed couchmark. WIP medic/medic-webapp#714

Added filter function to feed.

Changed some logging so if you are not in debug mode output is still
useful.