Add explicit page breaks before specific code examples

[pbrisbin]

Some code examples fall between pages and the page break looks bad. Once the content is totally settled, should look into a LaTex way to address this mis-formatting.

[calebhearth]

@trevororeilly mentioned something recently that leads me to believe that Paperback already makes an effort to prevent breaking of images or code over multiple pages.

[trevororeilly]

Yep, I could be off here but I think that's the case. I'll make a note to do some more digging and try to confirm.

[calebhearth]

@pbrisbin are you happy with how this looks?

[pbrisbin]

Thanks for bump @calebthompson I'll go through a read on my kindle soon and close or update these issues.

[pbrisbin]

Reading through on my Kindle, code samples do still span page-breaks in a many places, so whatever cleverness is in paperback, it doesn't seem to be working completely.

That said, the page-breaks didn't bother me nearly as bad as #76. So I'd be inclined to close this as "good enough" and focus on that issue first.

[jferris]

I was never able to get our Pandoc/LaTeX setup to isolate code blocks to a single page. For Ruby Science, I ended up going through and inserting manual page breaks for situations that turned out to be severely interrupted by automatic page breaks.