Adding very basic functionality.  My IVY configs are not fully correct.
Modified PigSerializer to properly handle basic persist (non-combining)
reduces.
Switched TridentBasicPerist over to a CombinerAggregator.
Brought in CombineWrapper and converted it over to Writable types.
Got the positive and negative elements in the reducer.  Now to stitch
them through Maps and work on the combiners.
Basic delta reduce works.  Now to work on inverting the combiners.
Got combine with deltas working with COUNT.
Added missing files from last commit and added GZPigSerializer.
Checking in before working on Join.
Fixed multiple inputs for maps.
Unions and joins work.  Fixed bug with negative pipeline in Map.
Got replicated join working.
Fixed execution to appropriately connect to hdfs when necessary.

Added missing JoinFixer.  Should probably manage the temp files better.
Fixed local replication to stash the files for long term storage.  Need
to fix ExecType because it is used to determine the FS types.  I think
I'm going to add an "in_storm" boolean on PigContext instead.
Swapped out most of the ExecType stuff as a boolean.
Fixed bug that broke pig STREAM elements.
Removing debug text from previous commit.
Added invert hooks to SUM.
Got the windowing "working".  CombinerAggregators didn't work quite
right and ReducerAggregators aggregate on batches.  Probably need to 
switch to plain Aggregators.  Going to sleep on it.
Committing changes so far.  Pulled out static subtrees from the MR plan
and starting to replace various portions with NOP Loads.  Re-organized
the package a bit to have an "io" section.