A abstract-blob-store compatible implementation built using leveldb as the storage backend

Description

Implements abstract-blob-store interface, uses leveldb as the backend storage. leveldb is pretty awesome btw

Disclaimer: As Max Ogden pointed out at https://github.com/maxogden/abstract-blob-store/issues/19#issuecomment-165211290, levelDB:

• LevelDB doesn't support streaming file writes, so values must fit in memory.
• In Google LevelDB compaction is notoriously inefficient in heavy write scenarios, so writing large quantities of data will likely result in lots of CPU thrashing.

API

See abstract-blob-store