Upgrade project to iOS 8
Remove lingering code

When I tried making a separate screen for writing the description this
code was necessary to deselect the table row that segued to that
screen.
Remove property to keep track of first responder

Having the new pin controller keep track of the first responder was
tedious. And this controller did not keep track of the tags text field
so tracking the first responder wasn't even complete. It's clearer to
just have each text field resign first responder.
Set project iOS Development Target to 8.0