bytes formatting only available in python >= 3.5
bytes formatting only available in python >= 3.5

Previous versions of python 3 don't support this; we thus first format things
with strings, and convert to bytes later.

Signed-off-by: Rodrigo Tobar <bd955c861cbec2e41c0959cf13c7f573fa307e58@icrar.org>

steve-ord/daliuge,steve-ord/daliuge,steve-ord/daliuge,steve-ord/daliuge,steve-ord/daliuge,steve-ord/daliuge,steve-ord/daliuge