Two more exif tags added

Hi,

I added two EXIF tags that my camera (Sony DSC-HX200V) fills and that are not recognized by ZenPhoto (SensitivityType and RecommendedExposureIndex).

For the first one, I also added the corresponding formatting code (Source : http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/EXIF.html).