add GetSize method to the v0v1 blockstore
add GetSize method to the v0v1 blockstore

fixes hidden merge conflict

License: MIT
Signed-off-by: Steven Allen <4068f0880b399410602d694b3cc711c8a8f4727e@stebalien.com>

ianopolous/go-ipfs,chriscool/go-ipfs,Luzifer/go-ipfs,chriscool/go-ipfs,ianopolous/go-ipfs,Luzifer/go-ipfs,ianopolous/go-ipfs,chriscool/go-ipfs,Luzifer/go-ipfs