Better support for large uploads
Currently recc will load all files into memory before uploading them to the remote. This can be seen most apparently in casupload. If you casupload
a large directory it load it all into memory before uploading. Recc could do a better job at doing this progressively.
It's possible that this might no longer be an issue for recc if there is a way to make recc use the cas functionality in buildbox-common. There might still be changes need over in buildbox-common to support progressive uploads.
In the normal case of using recc for a compilation, the number of rpcs should be kept to a minimum so it's likely that all in-memory is "OK" for that use case.