Fix up some CGFloat handling in NIAttributedLabel
Make UIResponder+NimbusCore.h import UIKit.h so that clients don't have to rely on importing it via PCH.
Import UIKit.h in NIActions.m because it references UIKit classes
Import UIKit.h in NIOverviewLogger.h because it references UIKit types
Merge pull request #517 from jverkoey/assorted-fixes

Miscellaneous header import and CGFloat fixes.