RFC6962-bis: Clarify error messages from logs

Currently the RFC only specify that error will be returned as HTTP errors.
Two aspects of error conditions should be clarified:
1. Clearly define which error conditions lead to each of the HTTP error codes. 
For example, a bad chain supplied to the add-chain method should always map to 
"400 Bad Request"  and requesting a proof by hash for a certificate that's not 
in the log should return "404 not found".
2. In the response body itself, the json struct containing error information 
should be well-defined (presumably containing a more detailed error code  and 
human-readable explanation).

Original issue reported on code.google.com by er...@google.com on 29 Jan 2014 at 3:48

alecmuffett / certificate-transparency

RFC6962-bis: Clarify error messages from logs #30