Wip claim 2#3

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mattbenjamin wants to merge 4 commits intomasterfrom

Commits on Dec 8, 2014

Include common/likely.h in buffer.h
Matt Benjamin
committed
Add safe-sharing to buffer::list and buffer::ptr.
Matt Benjamin
committed
Restore zero-copy buffers in OSD fast path.
Matt Benjamin
committed
Message::set_data cannot preserve constness.
Matt Benjamin
committed