Create sample project to demo row height estimation
Completed demo project to show the difference between estimation and not

Initial load time is a lot quicker. Scrolling is maybe slightly slower,
but that's due to the way we're slowing down the load.
Add code to calculate table load time
Updated load time calc code so it is only calculated on first view.
License headers
Added the images for the writeup
Completes writeup of tableview height estimation
Merge branch 'days/19-uitableview-rowheight-estimation'