Revert "Return 412 instead of 404 on bad sync."

This reverts commit e06d1d5f2df6a593380f791336af6acc0094e693.
raise 412 instead of 404 from sync log
add new django-no-exceptions dependency to travis
Merge branch 'master' into sync-log-412
Merge branch 'master' into sync-log-412
Merge pull request #226 from dimagi/sync-log-412

Sync log 412