Updated to support XCode 6.0 GM.

This includes the latest updates to the language specification but also alters the project settings for the playgrounds to target 'iossimulator' rather than 'macosx'. This was necessary as the release of XCode 6.0 GM broke playgrounds that targeted OSX.

This new configuration does work on both of the current versions of XCode (6.0 GM and 6.1 Beta 2)