Create boilerplate for presentation controller writeup
Add thumbnail
Change of heart

We'll cover presentation controllers later. Let's do the simple ones
first
Create sample single-page app for demoing alerts and popovers
License headers
Removing boilerplate
Created popovers via IB and via code
Update to demo using the PopoverPresentationControllerDelegate
Adds an alert view using the new alert controller
Added action sheet.

This is adaptive :)
This actually needs to be conditional
Updates existing code to make the presentation better.
Wrote introduction and conclusion
Completed writing about popover controllers
Completed writeup
Resized assets for blog upload
Fixing some typos
Merge branch 'days/21-alerts-and-popovers'