I added an optional parameter to allow the user to override a tap's sink mode. This is useful when you put flows into a cascade. http://docs.cascading.org/cascading/2.1/userguide/html/ch03s08.html#N20CA7
Refactor the Mode into a trait, add FlowState
 merge with develop
More cleanups, address review
Reduce default spill threshold back to 100k
Merge pull request #370 from adamilardi/SinkModeChanges

Sink Mode Changes
Merge pull request #464 from twitter/mode-trait

Refactor the Mode into a trait, add FlowState