Add a log file for everything that comes from error_logger.

This is mostly progress and crash reports so I called it "reports".

Change-Id: I1d467febb2cbe9063202a92865a2ca3af6667ec6
Reviewed-on: http://review.couchbase.org/33020
Reviewed-by: Artem Stemkovski <artem@couchbase.com>
Tested-by: Artem Stemkovski <artem@couchbase.com>