Fix bug in SQL key/value store.
Fix bug in SQL key/value store.

We can't cache and re-use PreparedStatement's because when you reuse one,
it invalidates the previously returned ResultSet. This causes an exception
if multiple iterators are created and then used later.

archiecobbs/jsimpledb,tempbottle/jsimpledb,archiecobbs/jsimpledb,tempbottle/jsimpledb,permazen/permazen,tempbottle/jsimpledb,permazen/permazen,archiecobbs/jsimpledb,permazen/permazen