Pull down some remote images. Partial fix for #86.

Pdf generation now fails with another error message.
Fix for #86 - save image with proper resolution, remove format nesting and fixed code blocks
Update README.md

Fixed typo: scripts/createPDFBook.pdf > createPDFBook.py
Update foreword/chapter.md

Suggesting some corrections to typos and punctuation.
Update foreword/chapter.md

(Another small capitalization correction.)
Merge pull request #87 from jasonalderman/master

Minor text edits on readme and foreword
Fixing links to code in graphics chapter