Review of Chapter 9 'Enhancing MirrorCell'
Merge pull request #8 from bencoman/MirrorCell

Review of Chapter 9 'Enhancing MirrorCell'
Correct typos in a variable name and a method name, and some minor grammar.
Merge pull request #9 from bencoman/Chapter8-ImprovingOurModel

Correct typos in a variable name and a method name, and some minor grammar