A Cascading scheme for combining intermediate sequence files

A cascading scheme for SequenceFile that uses EB's `DelegateCombineFileInputFormat`. 
This will allow us to turn on split combination for all intermediate jobs in a cascading pipeline (currently we can only turn it on for initial LZO sources).
I see, this makes sense. Just refreshed myself with whats happening here.. pretty mind bending MapredInputFormatCompatible is required for DelegateCombineFileInputFormat. It is not a must for DeprecatedMapredInputFormat.