dcm2niix converted_files duplicate entry

[mauriliogenovese]

Summary

Converting mosaic dti series with dmc2niix results in a duplicated output

Actual behavior

converted_files output contains twice the generated nifti file

Expected behavior

converted_files should contain a single entry

###Possible solution
_parse_files in Dcm2niix should check if the file is already in lists before appending

[effigies]

Patches are welcome.