Feature request: keep a local cache of filenames and MD5SUMs

[ncw]

When I sync a big directory to cloudfiles it spends ages going through every file and making the MD5SUM of them, even though they haven't changed before it transfers a byte of data.

It would be great if cloudfiles-sync could cache the MD5SUMs along with the paths, size and modification of each file. Then it could read this file quickly see to if any MD5SUMs needed updating which would save an awful lot of disk thrashing!