py: add bytes.replace
py: add bytes.replace

Signed-off-by: Sebastien Binet <be0c0d1298e63814a95fcb7523d1ca1345b4ca1f@cern.ch>

go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython