title: Exclude App Extension (WatchKit) from Xcode build script / xcodebuild
body: <p>The CI service we are using at the moment works from iOS 8.1 which (correct me if I'm wrong) does not support the Apple Watch / WatchKit. I've done some searching and poking around Xcode, but to no avail.</p>
  
  <p>I'm looking for a way to exclude my Apple Watch extension from the build - either through <code>Run Build Script</code> in Xcode, or what would be even better is a way to do it directly through the xcodebuild command.</p>
  
  <p>Anyone have any tips?</p>