Return false to georerferencer if any exception

This fixes #1354

The code was already there in order to capture a very specific
ContentGuesserException. I modified it to capture and log any exception.
I know the procedure to log the error is a bit controversial, but I
tested it and I'm open to discussion, if needed.
Merge remote-tracking branch 'origin/master' into make-importer-resilient-guessing
Merge pull request #1403 from CartoDB/make-importer-resilient-guessing

Return false to georerferencer if any exception