Updated recipes from chapter 15.
Updated notebook footer.
Updated footer in featured recipes.
Fixed links to featured recipes.
Update README.md
Fix recipe 7.8 (thanks to @mpelko). Close #9.
Merge branch 'master' of https://github.com/ipython-books/cookbook-code

Fix recipe 7.8.
Added errata page.
Minor fixes in errata page.
Fixed links.
Fixed layout issue in recipe 1.6.
Merge pull request #1 from ipython-books/master

Update from de original