Bring back the podspec

[arabold]

Not having a .podspec file makes forking and patching this repo more difficult than it should be IMO. Having a reference segment-appsflyer-ios.podspec shouldn't hurt:

Pod::Spec.new do |s|
  s.name             = "segment-appsflyer-ios"
  s.version          = "1.1.8"
  s.summary          = "AppsFlyer Integration for Segment's analytics-ios library."

  s.description      = <<-DESC
                       AppsFlyer is the market leader in mobile advertising 
                       attribution & analytics, helping marketers to pinpoint
                       their targeting, optimize their ad spend and boost
                       their ROI.
                       DESC

  s.homepage         = "https://github.com/AppsFlyerSDK/segment-appsflyer-ios/"
  s.license          = { :type => 'MIT' }
  s.author           = { "Golan" => "golan@appsflyer.com" }
  s.source           = { :git => "https://github.com/AppsFlyerSDK/segment-appsflyer-ios.git", :tag => s.version.to_s }
  s.social_media_url = 'https://twitter.com/Appsflyer'

  s.ios.deployment_target = '8.0'
  s.tvos.deployment_target = '9.0'

  s.framework = 'Security'

  s.source_files = 'segment-appsflyer-ios/Classes/**/*'

  s.dependency 'Analytics', '~> 3.5'
  s.dependency 'AppsFlyerFramework', '~> 4.5.12'
end

[golts]

Added pod spec back.