[algorithms] Overlap interface revision

* Now it accepts not only binary files, also ROI files with multiple
  labels.
* Volumes can be handled in voxel units (as formerly) and mm3
* Keeps backwards compatibility of outputs and inputs
fix: topup when out_base is a path
Fixes #933
moved the import inside the constructor
Add tests
fix: change where nlmeans check is made
Merge remote-tracking branch 'upstream/master' into fix/topup

* upstream/master: (82 commits)
  tiny typo
  another attempt at fixing bash conditionals
  fixed bash conditionals
  added no dep install version. we'll be testing on both.
  Added xor option in Camino connectivity for robustness
  Conmat test function
  Added more connectivity matrix options in Camino interface
  Fixed tests.
  remove deb packages installation
  added apt caching
  fix: d3 change.
  switched to six.string_types for string type checks
  added external package: 'six'
  Mention AddNoise in the changelog
  Remove d3.min.js dependency
  Log cleanup
  Fixed tests
  Update README.rst
  Update links_names.txt
  Update index.rst
  ...
Merge pull request #925 from oesteban/enh/OverlapOfROIs

[algorithms] Overlap interface revision
typo in nipype/workflows/dmri/fsl/epi.py
Merge pull request #937 from cni-md/master

typo in nipype/workflows/dmri/fsl/epi.py
Merge remote-tracking branch 'upstream/master' into fix/bedpostx

* upstream/master:
  typo in nipype/workflows/dmri/fsl/epi.py
  Add tests
  [algorithms] Overlap interface revision
Merge remote-tracking branch 'private/fix/dipy_tests'

* private/fix/dipy_tests:
  moved the import inside the constructor
  Fixes #933
Merge remote-tracking branch 'upstream/master' into fix/bedpostx

* upstream/master:
  moved the import inside the constructor
  Fixes #933
Merge pull request #928 from satra/fix/topup

fix: topup when out_base is a path
fix: clean up bedpostx and xfibres implementations
Merge remote-tracking branch 'upstream/master' into fix/dipy

* upstream/master:
  typo in nipype/workflows/dmri/fsl/epi.py
  tiny typo
  Add tests
  another attempt at fixing bash conditionals
  fixed bash conditionals
  added no dep install version. we'll be testing on both.
  Added xor option in Camino connectivity for robustness
  Conmat test function
  Added more connectivity matrix options in Camino interface
  Fixed tests.
  remove deb packages installation
  fix: topup when out_base is a path
  [algorithms] Overlap interface revision
Merge pull request #939 from satra/fix/dipy

Fix/dipy
Merge remote-tracking branch 'upstream/master' into fix/bedpostx

* upstream/master:
  fix: change where nlmeans check is made
  fix: topup when out_base is a path
tst: cleaned auto tests and imports
tst: fixed all failing tests