Cleanup iterator and honor `options.as_buffer=false` in `key()`, `value()`, and `current()`
Cleanup iterator and honor `options.as_buffer=false` in `key()`, `value()`, and `current()`

mikepb/node-leveldb,maxogden/node-leveldb,maxogden/node-leveldb,my8bird/node-leveldb,maxogden/node-leveldb,my8bird/node-leveldb,my8bird/node-leveldb,mikepb/node-leveldb