Don't store CID in disk if it maps to an all zero chunk #7
Description
If a chunk is made up of all zeroes it will always map to the same CID, so we don't need to actually store it.
This might be relatively common, as chunks are filled with zeroes when padded or when a disconnection happens.
To implement
Have a "zero cid" global that is computed on an init function for one of our modules (Probably "resource pool"), which will make an all zero buffer and compute the CID to compare it.