Start playing with yhat
Add annual mean pollution example
More yhat stuff
Merge branch 'master' of github.com:DataScienceSpecialization/courses into dataprod

* 'master' of github.com:DataScienceSpecialization/courses:
  Added the hunger.csv file
  Edited the project file. It's still different on Coursera
  updates
  Typo in Lec 01-01-03, Afriad -> Afraid
  updated jeff's lectures
  Makefile for creating PDF slides
  Talk about DSS sequence
  Update
  Update week 4 announcement
Merge branch 'dataprod'

* dataprod:
  More yhat stuff
  Add annual mean pollution example
  Start playing with yhat