Merge pull request #24 from rdpeng/master

yhat stuff
update
Merge branch 'master' of https://github.com/DataScienceSpecialization/courses
renamed prediction course
update
update ghpages
nojekyll
Merge branch 'master' of https://github.com/DataScienceSpecialization/courses into gh-pages
update
Merge branch 'master' of github.com:DataScienceSpecialization/courses

* 'master' of github.com:DataScienceSpecialization/courses:
  update
  nojekyll
  update ghpages
  update
  renamed prediction course
  update