Merge pull request #990 from blakedewey/master

Update and Clean ants.segmentation

Author: satra

CHANGES

@@ -1,6 +1,9 @@
 Next release
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+* ENH: Updated N4BiasCorrection input spec to include weight image and spline order. Made 
+	   argument formatting consistent. Cleaned ants.segmentation according to PEP8.
+	   (https://github.com/nipy/nipype/pull/990/files)
 * ENH: SPM12 Normalize interface (https://github.com/nipy/nipype/pull/986)
 * FIX: Utility interface test dir (https://github.com/nipy/nipype/pull/986)
 * FIX: IPython engine directory reset after crash (https://github.com/nipy/nipype/pull/987)