HDF5IndexAndConvert: Fix the MongoDB collection name (Images -> images)
HDF5IndexAndConvert ConvertHDF5ToPNG(): Disable bogus Stat() check

The if condition is probably reversed as it triggers anytime but when
the file already exists. I'm just commenting it out, maybe Michael will
find a proper fix.
HDF5IndexAndConvert GetHDF5Autorectify(): Tidy up, add data by baseName rather than originalPath

That will allow me to easily re-run autorectification without re-importing everything.