Fixes typos.
Elaborate the explanation for NIPY.
Cut out the fluff.
Merge pull request #673 from arokem/nipy-descr

Elaborate the explanation for NIPY.
Merge pull request #669 from BernhardKonrad/patch-1

Fixes typos.
Rob Davey
Merge branch 'master' of github.com:swcarpentry/site