Based on cnstoll's change to fix text properties in iOS 7

https://github.com/mutualmobile/nui/commit/42f9c63165f6a43e34edb4d157b3387487cdf644

With the following modifications added:
- warnings for use of deprecated selectors is disabled selectively
- text color key is specified (without this the demo was crashing for me)
- a protocol is introduced for objects that observe orientation changes (this is to remove an unknown selector warning when setting up the observers)