Non-functional changes in scheduler.py for python3
Non-functional changes in scheduler.py for python3

Mainly exception declaration, print statement replacement by logger, and proper
print statement usage.

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