Added a WINDOWS Version of the Network R Script.

shell("dir /B *csv", intern=TRUE) is the way to list a directory on
Windows.
Week 2 Activities - Sample Data Set
Finalized Data Set
powerpoint change
Week Three Python
New Files for Week 3  / Boston Marathon Data - 2013

Top 1500 finishers.
Merge pull request #1 from The-Art-of-Big-Social-Data/master

update