Two phase handoff - fixes 373

Fixes #373.

DO NOT MERGE UNTIL AFTER #46. Two-phased push without incremental push will result in copying all of the data twice.
We had discussed before avoiding the word orchestration due to the baggage that comes with it in the very crowded orchestration market.  Is there another word we could substitute in that would still get the point across and still be accurate?  Maybe "Data-focused clustering" like Luke used in his blog? https://clusterhq.com/blog/data-focused-docker-clustering/