Create plots_png

The png plots produced by the r code

plot 1
https://cloud.githubusercontent.com/assets/10058613/5332684/5e989c6a-7e57-11e4-8a51-279fed1df155.png

plot 2
https://cloud.githubusercontent.com/assets/10058613/5332686/60f63a30-7e57-11e4-80c7-01631f8d1d83.png

plot 3
https://cloud.githubusercontent.com/assets/10058613/5332689/6562d47a-7e57-11e4-907f-8f634fdd8b9c.png

plot 4
https://cloud.githubusercontent.com/assets/10058613/5332691/688bd048-7e57-11e4-85f3-474e17701904.png