Option for separate storage class for small objects

[larkost]

Currently when uploading objects to S3 you can specify --storage-class in order to set the class for all objects you send. But there are a number of storage classes, such as all three of the "Glacier" levels where objects smaller than 128KiB probably will cost more if put into that class, and probably should remain at a higher level.

So it would be advantageous if there were a --storage-class-small option to specify a different class for smaller objects. I would be Ok if this size were hard-coded to 128KiB, but would not be against that default plus an option to set the value; something like --storage-small-size 64KiB.