Added c.t.DecoratorTap class to simplify wrapping a given c.t.Tap instance with additional meta-data. Updated c.f.p.FlowPlanner to allow both intermediate temporary c.t.Tap or any c.p.Checkpoint tap to be decorated by a configured c.t.DecoratorTap class via new c.f.FlowConnectorProps properties.
Added c.t.h.DistCacheTap a decorator for a c.t.h.Hfs instance that uses o.a.h.f.DistributedCache to read files transparently from local disk. This is useful for c.p.HashJoins.
Fixed issue where c.p.a.UniqueBy was not honoring the c.t.Hasher interface.
Updated c.t.h.DistCacheTap to support simple file globing as provided by c.t.h.Hfs.
rebased on 2.6, squashed, added TraceUtil (may not be with the api risk)
Fix broken "rebasedpublic" code

The previous commit had broken, uncompilable code. This commit fixes
it.
Removed apiCall.

This commit removes apiCall as a distinct field. Instead it
puts the apiCall into the trace field. It is separated from the stack
trace of the user's code by an @ symbol. This makes the trace
look very similar to what Fluid currently produces. TraceTest is updated
and shows the new behavior.