Refactor object PUT to make EC easier to add

EC fragment archives need to go on the right primary nodes; that is,
fragment archive 0 needs to go on primary node 0, 1 on 1, and so
forth. Handoff nodes, however, are unordered.

This commit plumbs the index through to the proxy ObjectController's
PUT method as well as adds a (very simple) transform for replicated
data storage. Hopefully, this provides an easy integration point for
EC to use.

Change-Id: I72e6f313b12d7d4611fd95109ba66c8df8c8fa0f
Merge "Refactor object PUT to make EC easier to add" into feature/ec