Include 'source' attribute in the podspec
The new version of Cocoapods requires it even when using the podspec locally.
diff --git a/Protobuf.podspec b/Protobuf.podspec
index 73a6022..02c8372 100644
--- a/Protobuf.podspec
+++ b/Protobuf.podspec
@@ -11,6 +11,9 @@
s.license = 'New BSD'
s.authors = { 'The Protocol Buffers contributors' => 'protobuf@googlegroups.com' }
+ s.source = { :git => 'https://github.com/google/protobuf.git',
+ :tag => "v#{s.version}" }
+
s.source_files = 'objectivec/*.{h,m}',
'objectivec/google/protobuf/Any.pbobjc.{h,m}',
'objectivec/google/protobuf/Api.pbobjc.{h,m}',