Example-project leaks instances of TTOpenInAppActivity

Reproduce:

• Start the app in instruments with the Allocations-instrument
• Tap on "Open In ..."
• Choose the "Open in ..."-action
• Close popover
• Repeat and check the growing number of persistent instances of TTOpenInAppActivity

I think that the documentInteractionControllerWillPresentOpenInMenu-delegate-implementation is missing a call to [self activityDidFinish:NO].
Though, it will also leak when the iPad gets rotated while the UIDocumentInteractionController is open. This is a bug in iOS, you may want to duplicate the following issue https://openradar.appspot.com/radar?id=5060950520496128.

[honkmaster]

Duplicated the issue.