Get rid of ShareHolder.
Get rid of Shareable.
Get rid PendingRows; all we need is a vanilla Queue.
qp.expression.BoundExpressions -> type.value.ValueRecord.
merge MMcM: Rip out row memory management

Merge pull request #960 from MMcM/akiban-server/remove-row-sharing
https://github.com/FoundationDB/sql-layer/pull/960