Exclude GCDWebServerPrivate.h from Podspec

GCDWebServer.podspec

@@ -22,6 +22,7 @@ Pod::Spec.new do |s|
   
   s.subspec 'Core' do |cs|
     cs.source_files = 'GCDWebServer/**/*.{h,m}'
+    cs.private_header_files = "GCDWebServer/Core/GCDWebServerPrivate.h"
     cs.requires_arc = true
     cs.ios.library = 'z'
     cs.ios.frameworks = 'MobileCoreServices', 'CFNetwork'