[xcode] add iOS and ATV2 Target to main Xcode project
* iOS Target added
* ATV2 Target added
* add build phases from iOS project
* add build phases from ATV2 project
* factor out most of the configuration into xcconfig files
  this should help in tracking down changes in the build configs,
  make diffs easier and such.
* provide a xcconfig cascade for the project level (Common -> Debug/Release)
  as well as on the target level (App -> App-OSX/App-iOS/App-ATV2)
* add xcconfig and after buildstep scripts to xcode for easy editing
[xcode] move all after buildsteps into external 'command' shell scripts for easy diffs
[ios] remove unused XBMC-iOS and XBMC-ATV2 xcodeproject
[jenkins] adjust build steps to point to iOS and ATV2 Target for using the new merged xcode project
[doc] - updated READM.ios for using the merged xcode project
[xcode] remove UnrarXLib{.sln,.vcproj} from xcodeproject