Delete blank line in code
Made reference link live
Chapter 3 typo correction

1.  replace "that is does" with "that this does"
2.  add "a" to "using loss function"
3. replace "parameter of interested" with "parameter of interest"
Correct typos

1. "scraping" replaces "scrapping"
2. Correct spelling of equivalence
3. Add hyperlink for Reference 2
Merge pull request #151 from williamscott/master

Minor editing changes to chapters 2 and 3