Base class for FuzzyOverlap misc tool

Some details are still to be fixed
Working version
Added inputs&outputs descriptions

PR #622
Run autopep8 on misc.py

In-place run of the standard tool. Ref #662
PEP8 for the whole interface

Fixed all errors. #622
Added dummy files so doctest doesn't fail

Files added in response of https://github.com/nipy/nipype/pull/622#discussion_r5921360
Fixed filenames in documentation

Minor change, as the names were not descriptive.
Merge pull request #622 from oesteban/enh/FuzzyOverlap

Fuzzy overlap Jaccard and Dice indices computation