Issue 419 more logging
Created by: MikeYalter
https://github.com/CrossRef/rest-api-doc/issues/419 feed api doesn't do much for logging, and where it does, doesn't include necessary information. Changes:
- log what DOI was pushed to what file name
- once unixsd file is parsed, write out the successful parse and DOI
- if a failure occurs within processing, log the failure and exception.