Simplify the introduction paragraph.
Simplify the introduction paragraph.

vsoch/nipy.github.com,arokem/nipy.github.com,vsoch/nipy.github.com,arokem/nipy.github.com,arokem/nipy.github.com,vsoch/nipy.github.com,lesteve/nipy.github.com,vsoch/nipy.github.com,lesteve/nipy.github.com,lesteve/nipy.github.com