Update top-level 'sim preferences path' docs
Don't try to a token in NSUserDefaults

Unreliable and unnecessary
Branch on iOS version to find plist in CoreSimulator
Update code comments
Remove unused helper methods
Merge pull request #87 from calabash/feature/more-simulator-preferences-fixes

Fix UIA :preferences strategy for Xcode 6.1 and iOS < 8.1 simulators