Code blocks

Hey, @kennethreitz!  Love your work, and this book.  :)

I made some “janitorial” type edits here. They are almost entirely related to specifying the syntax for code-blocks.  

I figured I’d start simple, because I’m not used to writing in ReST.  That said…I honestly have no idea if I broke anything.  (ReST is powerful, but I can never get the syntax straight from memory, so I usually prefer markdown). 

If I did break something, just comment on the broken part(s) in the diff, and I’ll fix it up.  

If this works out, I have some more edits in the works…