.. and implementing it in-memory ..
This PR separates InMemoryStorage in 2 classes:
Other possible subclasses extending DocumentBinaryStorage would be a krati storage, maybe a BerkeleyDB storage, or even a LevelDB storage.
BTW, I already have a working Krati version based on this branch on dbuthay/indextank-engine@2718a9e
making InMemoryStorage an abstract DocumentBinaryStorage .. and imple…
…menting it in-memory