Minor cleanups

[effigies]

Running make check-before-commit prompted the following cleanups.

Changes proposed in this pull request

• Renames test_dcm2nii.py to test_extra_dcm2nii.py, as OSX's case insensitivity causes make specs to remove test_auto_Dcm2nii.py. Issue introduced in Fix/dcm2niix #2498.
• Whitespace cleanups.

[codecov-io]

Codecov Report

Merging #2519 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2519      +/-   ##
==========================================
+ Coverage   66.84%   66.88%   +0.04%     
==========================================
  Files         327      327              
  Lines       42479    42479              
  Branches     5268     5268              
==========================================
+ Hits        28393    28411      +18     
+ Misses      13381    13366      -15     
+ Partials      705      702       -3

Flag	Coverage Δ
#smoketests	50.83% <ø> (+0.3%)	⬆️
#unittests	64.23% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
nipype/interfaces/afni/preprocess.py	81.03% <ø> (ø)	⬆️
nipype/pipeline/engine/nodes.py	83.91% <0%> (+0.33%)	⬆️
nipype/utils/provenance.py	84.71% <0%> (+1.27%)	⬆️
nipype/workflows/fmri/spm/preprocess.py	72.44% <0%> (+12.24%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ab3ea2d...15274fb. Read the comment docs.

[mgxd]

LGTM