Typo fix: Humanizes -> Humanize
Spaaace -> space

Sabotaged by: https://gist.github.com/GeorgeHahn/8821738
Merge pull request #79 from GeorgeHahn/patch-1

Readme typo fix: Humanizes -> Humanize
NumberToWordsExtension.ToWords add ability to convert billions
Convert ToWords' tests to theory
Add more test for .ToWords() method.