LevelDB Library

We have existing bindings for LevelDB

• Additional tests are needed
• A few methods need to be wrapped better.
  • leveldb-approximate-sizes
  • leveldb-iter-get-error
• Write documentation?
• Use finalization to handle tearing things down correctly?
  • This may be tricky in the case where LevelDB may be holding on to something like writeoptions in a writebatch.