Switching Notifications to UITextView

@aerych you're **THE** DTCoreText expert. May i bother you with a quick review?

Notifications with (long) comments weren't being rendered, due to a **DTAttributedLabel** limitation. Instead of subclassing and implementing CATiledLayer, i opted for just switching over to UITextView.

*WPDynamicHeightTextView* implementation was required, since the `intrinsicContentSize` property of *UITextView* doesn't return the content size.

Thank you!