Improve logging

Now shows a single csv parsing error text and source file name (w/o extension, but still useful) in the Feed Status line when there's a csv parsing error. No line numbers, the csv parsing library that is in use doesn't give us that. And I tried at least one other, to not very good results.

I did try another feed that was already working for me (dc.zip) and it still works, so hopefully not more broken than before. Please run the tests after review.

Assigning to @cap10morgan 
Should we use `if (msg.messageId === -1) { ... }` here (i.e. the triple-equals op)?