typo fixes

First off, let me say this was a fantastic read!  I'm still learning (aren't we all) JS, but this book helped clear up a lot of misconceptions, and definitely has me thinking about OLOO (which I find easier to understand!)

*In addition to these minor typos, I want to point out a couple confusing lines that might need addressing:*

- In chapter 6, around line 497, you have some code that I think is wrong.  I believe showDialog should  have "= function" there, and it currently doesn't.
- Also, in the same chapter, at around 537, I believe you meant to override LoginController, not AuthController.

Thanks!