Enabled Xcode 7 code coverage on project

Author: aaronschubert0

AsyncDisplayKit.xcodeproj/xcshareddata/xcschemes/AsyncDisplayKit-iOS.xcscheme

@@ -26,7 +26,8 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      shouldUseLaunchSchemeArgsEnv = "YES">
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      codeCoverageEnabled = "YES">
       <Testables>
       </Testables>
       <AdditionalOptions>