Add 'Explore Flask' by Robert Picard

This recipe uses the public web site for the book, rather than the book's GitHub repo.
Add CS183 (Blake Masters' notes from Peter Thiel's class)
Merge pull request #9 from rahimnathwani/master

Add 'Explore Flask' by Robert Picard and 'CS183'
Add Learn_Vimscript_the_Hard_Way.recipe

- update readme for #9
- add learn vimscript the hard way