Data example creates mdf5sums.txt when downloading remote data

[hrobarts]

Description

When downloading remote data using dataexample e.g.

dataexample.KORN.download_data('.')

the download generates an mdf5sums.txt file which is not deleted after checking. We should remove the checksum file.

Environment

import cil, sys
print(cil.version.version, cil.version.commit_hash, sys.version, sys.platform)