Fix closing upon download completion in fetcher
Merge pull request #226 from Garyfallidis/fix-vtk6

SetInput in vtk5 is now SetInputData in vtk6
NF: Added histogram based brain or foreground extraction
DOC added docstring example in hist_mask
DOC tiny change
BF: Minor change in Mmarkov.py replaced offending hyphen
Updated Stefan's suggestions on github
BF: np.percentile didn't work correctly with real brain
added a brain extraction example on the Standford Data
DOC: initiating brain_extraction example
Added many brains for checks
NF: Added histogram based brain or foreground extraction
DOC added docstring example in hist_mask
DOC tiny change
Updated Stefan's suggestions on github
BF: np.percentile didn't work correctly with real brain
added a brain extraction example on the Standford Data
wip
wip brain_extraction.py
added an example