Adding csv support for the GT file and the Resume Output File

As part of the FITS Blitz project (SPRUCE) we might need your tool. As Excel files are not always straightforward for manipulation I am sending you this patch with support for csv. And some minor bug fixes. 

The current configuration should still work.
The correct input/output strategy is inferred by the extension of the ground truth file and the output file.
You can use a combination of csv and xls.