STYL: testUtils: Improve test outputs
STYL: testUtils: Improve test outputs

* Update feature name in testing output to reflect the feature class.

* write "N/A" string when no data can be found

* write csv as text file using `w` instead of `wb` (this should help with
  the transition to py3)

Radiomics/pyradiomics,Radiomics/pyradiomics,Radiomics/pyradiomics,Radiomics/pyradiomics