Remove headers_build_phase from example's Podfile

Fixes #106

example/ios/Podfile

@@ -59,13 +59,9 @@ end
 
 post_install do |installer|
   installer.pods_project.targets.each do |target|
-    target.headers_build_phase.files.each do |file|
-      file.settings = { 'ATTRIBUTES' => ['Public'] }
-    end
     target.build_configurations.each do |config|
       config.build_settings['ENABLE_BITCODE'] = 'NO'
       config.build_settings['SWIFT_VERSION'] = '4.0'
     end
-
   end
 end