Fix the path for windows powershell

Typo in pythonpath for powershell
Merge branch 'master' of github.com:practical-neuroimaging/pna-notebooks

* 'master' of github.com:practical-neuroimaging/pna-notebooks:
  BF: fix path name in windows path setting
  Nipype ANTS sketch based on example
  Updating motion correction notebook
  BF: added back preconditioning to params
  NF: add template registration file
  Notebook on motion correction
  NF: added Dan's day12 answers with some edits
  Add Dan's files for answers
  Update mutual infornation notebook