Merge pull request #86 from tumblr/feature/add-back-notification-obse…

…rvation

Add back notification observation that was stupidly removed in 2.0.0

Even better conditional compilation

Merge pull request #81 from tumblr/feature/conditional-compilation-fo…

…r-extension-targets

Conditionally compile references to UIApplication only when not building for an extension target

Only include UIKit on iOS

Version bump

Merge pull request #45 from tumblr/setObject-crashes

Fixes a few small setObject:forKey: exceptions that can be triggered