Publishing API now expects a 'publishing-app' field

This expectation was added after short-url-manager was built, but
the change was causing redirect registration to fail since the
API change
Merge pull request #9 from alphagov/fix-publishing-api-missing-field

Publishing API now expects a 'publishing-app' field
Log publishing API errors, for easier debugging

Previous the exception was handled, to provide better UI, which is
good, but meant the exception was not logged and not available
for debugging via Errbit.

This ensures we log the exception for debugging and still handle
the exception to provide better UI
Merge pull request #10 from alphagov/api-failing-logging

Log publishing API errors, for easier debugging