Verify blob usage #285
Description
Our benchmarks of 10MB writes strongly suggest that blobs aren't being properly utilized for storage of large records, as they should. In addition the benchmark seems to only produce .sst files, and I believe there is a distinct file extension for the database files that house blobs. We should create a test that verifies that after writing a 10KB record to the database, that the rocksdb.num-blob-files database property increases. This is dependent on #256 to access that database property.