Add missing files to podspec

CryptoSwift.podspec

@@ -14,6 +14,6 @@ Pod::Spec.new do |s|
   s.osx.deployment_target = "10.9"
   s.watchos.platform = :watchos, '2.0'
   s.watchos.deployment_target = "2.0"
-  s.source_files  = "CryptoSwift/*.swift"
+  s.source_files  = "CryptoSwift/**/*.swift"
   s.requires_arc = true
 end