switch xcode to manual signing for Unity 5.3

xcode_manual_signing.rb

require 'xcodeproj'

# utility for unity 5.3 to use xcode 8 with manual signing
# for Unity 5.4 see https://gist.github.com/echorebel/b073bc7858c36218610e63f2b7664639
# Usage:
# ruby xcode_manual_signing.rb -p <path/to/xcode_project>
# default path is Build/iOS/Unity-iPhone.xcodeproj

args = ARGV
project_path = 'Build/iOS/Unity-iPhone.xcodeproj'
args.each_with_index do |arg, index|
  case arg
  when '--project_path', '-p'
	project_path = args[index + 1]
	unless File.exist?(project_path)
	  abort('There is no file at specified path.')
	end
end
end

project = Xcodeproj::Project.open(project_path)
target_id = project.targets.first.uuid
attributes = project.root_object.attributes['TargetAttributes']
attributes[target_id] = {'ProvisioningStyle' => 'Manual'}
target_attributes = attributes[target_id]
project.save