OHAttributedLabel doesn't work with autolayout

If you create an OHAttributedLabel without a frame and position it using autolayout, it has 0 height. This is because when intrinsicContentSize is invoked, attributedText is not set in the UILabel superclass, so the label appears to be empty. Setting the attributedText on the UILabel superclass allows it to calculate the intrinsicContentSize, without any apparent side effects.