Moved async settings instructions to top of article.
Updated promises info.
Attempt to make file paths to demo work by renaming them demo.html instead of index.html.
Added additional media query for some of the side-by-side comparisons.
Added new section on using the console with the async call stack.
Merge pull request #1045 from pearlchen/devtools-async-call-stacks

Updates to "Debugging Asynchronous JavaScript with Chrome DevTools"