Compute length of content written by OpenCloud SDK
Compute length of content written by OpenCloud SDK

The OpenCloud SDK is broken: the object returned by `uploadObject()`
method contains a bad ContentLength. Thus the best is to compute
the content size using `Util\Size::fromContent()` method.

NiR-/Gaufrette,KnpLabs/Gaufrette,KnpLabs/Gaufrette,NiR-/Gaufrette