Fix ascii conversation errors

The bit in the _report method fixes at least the traceback in Report > Monthly Report for Last Month. I haven't tested the part in daily_report, but the code looks really similar. Printing in a file the way it's done here should just be binned really.

The real fix would probably be to not open this file in binary, but that's a bit more involved than this.

Signed-off-by: Maxime “pep” Buquet pep@bouah.net