Added python2-relevant code
Added python2-relevant code

The python2 version of sercore was not registering the Writer/Reader
types during initialization.

simleo/pydoop,crs4/pydoop,elzaggo/pydoop,elzaggo/pydoop,crs4/pydoop,simleo/pydoop,elzaggo/pydoop,simleo/pydoop,crs4/pydoop,crs4/pydoop,elzaggo/pydoop,elzaggo/pydoop,simleo/pydoop,simleo/pydoop,crs4/pydoop