BF: Run make specs with CWD in PYTHONPATH

[effigies]

Not an expert at Makefiles, so this may not be the best way to go about this, but it does seem to set the PYTHONPATH so that make specs is run on the working directory, rather than an installed nipype.

Fixes #1348.

[effigies]

Might as well run make specs and include the updated tests with this patch.

[codecov-io]

Codecov Report

Merging #1813 into master will increase coverage by 0.38%.
The diff coverage is 98.63%.

@@            Coverage Diff             @@
##           master    #1813      +/-   ##
==========================================
+ Coverage   72.71%   73.09%   +0.38%     
==========================================
  Files        1059     1064       +5     
  Lines       52550    53316     +766     
==========================================
+ Hits        38212    38972     +760     
- Misses      14338    14344       +6

Flag	Coverage Δ
#unittests	73.09% <98.63%> (+0.38%)	✅

Impacted Files	Coverage Δ
...aces/freesurfer/tests/test_auto_FSCommandOpenMP.py	100% <100%> (ø)	✅
...ces/ants/tests/test_auto_AverageAffineTransform.py	92.85% <100%> (+0.54%)	✅
.../interfaces/freesurfer/tests/test_auto_Resample.py	92.85% <100%> (+0.54%)	✅
...rfaces/freesurfer/tests/test_auto_SurfaceSmooth.py	92.85% <100%> (+0.54%)	✅
nipype/interfaces/dipy/tests/test_auto_CSD.py	92.85% <100%> (+0.54%)	✅
...interfaces/freesurfer/tests/test_auto_SegmentWM.py	92.85% <100%> (+0.54%)	✅
...ype/interfaces/ants/tests/test_auto_JointFusion.py	92.85% <100%> (+0.54%)	✅
...faces/freesurfer/tests/test_auto_RobustRegister.py	92.85% <100%> (+0.54%)	✅
nipype/interfaces/fsl/tests/test_auto_B0Calc.py	92.85% <100%> (+0.54%)	✅
...ipype/interfaces/brainsuite/tests/test_auto_Bse.py	92.85% <100%> (+0.54%)	✅
... and 697 more

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[effigies]

@satra Do you want to have a quick look? This is just a quick fixup to make make specs work properly for devs with an installed copy of nipype and/or working in Python 3.

[satra]

the primary reason we were using python 2 was because of unicode issues. however, if we include unicode_literals at the top of template, we can generate the same tests from either py2 or py3 by modifying the test generator a bit.

the main point of these auto-tests were to create an easy visual check for changes in input/outputspec api and to instantiate each object in the absence of consistent doctests. the former we can capture through a good PR review. the latter would require some work to go through all interfaces. so if we can achieve these two things somehow, it would be good.

[effigies]

7ff705f makes py2/py3 behavior equivalent. I'm not entirely sure what you're suggesting for instantiating each object... Does the current system not do that?