Do not set contentScale based on UIWindow.

For current devices with 'retina' resolution (2 pixels/1 point),
the contentsScale of a layer needs to be set to 2.0. The mainScreen
singleton has the correct scale factor, but the UIWindow.contentsScaleFactor
is not always correct. Setting the layer's contentsScale based on
the UIWindow can result in low-res rendering on retina displays.

The window's contentScaleFactor does not always contain the correct
Fix Demo & Library settings for iOS / Xcode 5

There was a mismatch between which archs were being built between
the demo project and library.
Add a .gitignore file for Xcode 4 & 5.
Add xcshareddata subfolders of project.workspace

These should be shared for everyone who checks out the project.
Remove support for 64-bit arm.

We need a deployment target of 6.1 for now.
Update project settings for Xcode 5.

Always build multiple archs for all settings.
Adding KVO for the playing property in SwiffPlayhead
Only build active arch for Debug/Profile configs.
Building library universal even in debug