Unify big payload behaviour

$ dd if=/dev/zero of=blob25m bs=1M count=25

25+0 records in

25+0 records out

26214400 bytes (26 MB, 25 MiB) copied, 0.00358114 s, 7.3 GB/s

$ dd if=/dev/zero of=blob45m bs=1M count=45

45+0 records in

45+0 records out

47185920 bytes (47 MB, 45 MiB) copied, 0.00602986 s, 7.8 GB/s

$ cbc cp -Ucouchbase://192.168.1.10/default blob25m

blob25m              The object requested is too big to store in the server (0x4)

$ cbc cp -Ucouchbase://192.168.1.10/default blob45m

blob45m              A badly formatted packet was sent to the server. Please report this in a bug (0x4b)