and pruning stale records in secondary databases.
Closes #144
Closes #158
Fixed bug where we modify key or pkey or data if we return errors and
we really just pruned stale records.

Added test to verify we have no memory leaks caused by these issues.

git-svn-id: file:///svn/tokudb@1019 c7de825b-a66e-492c-adef-691d508d4ae1