update to version 2.1.6
Updated c.s.h.HadoopStepStats counter caching strategy to make a final attempt even if max timeouts have been met. Added "cascading.step.counter.timeout" property to allow tuning of timeout period.
minor updates to exception messages
additional log messages for spilling and tuple serialization
update spill tests to use custom serializations
Fixed issue where Fields.REPLACE on an incoming Fields.UNKNOWN could result in a java.lang.ArrayIndexOutOfBoundsException during runtime.
print verbose in declared fields
Updated c.t.Fields#size() to return Fields.NONE on size == 0, instead of failing.
add version info to dot file
call gc before logging
Fixed issue where a j.l.StackOverflowError would be thrown if the Hadoop mapred.input.format.class property was not set.
Fixed issue where join field level c.t.Hasher instances were not honored during a c.p.HashJoin.
updated version and platform release printing methods
Updated c.p.SubAssembly to throw UnsupportedOperationException on #getConfigDef() and #getStepConfigDef() calls.
Merge remote-tracking branch 'upstream/wip-2.1' into 2.1