Add more information to bulk failure messages

[jbaiera]

In most cases, when Elasticsearch returns error codes for documents that are part of a bulk operation, the top level message is sufficient to be logged, but in some cases the top level message can be a not very helpful string like "failed to parse".

When a bulk operation fails and we capture information about the failures, we should log as much of the exceptions as we can along with the records that caused them.

[danielyahn]

@jbaiera, has this issue been improved?