* scrooge-runtime backward compatible, bringing back FinagleThriftClient, FinagleThriftService, ThriftStructCodec.encoder and ThriftStructCodec.decoder. They are marked as @deprecated
* Add ThriftStructMetaData to iintrospect generated ThriftStruct (copied from Jeremy Cloud's change to scrooge-runtime 2)
* rename ScroogeOption to just Option
*  bump version to 3.0.6, update CHANGELOG

RB_ID=125457