Fix absolute URLs to point to main repository instead of my fork.
Fix absolute URLs to point to main repository instead of my fork.

udacity/ggplot,kmather73/ggplot,eco32i/ggplot,benslice/ggplot,assad2012/ggplot,xguse/ggplot,benslice/ggplot,ricket1978/ggplot,Cophy08/ggplot,andnovar/ggplot,smblance/ggplot,xguse/ggplot,bitemyapp/ggplot,mizzao/ggplot,mizzao/ggplot,wllmtrng/ggplot,ricket1978/ggplot