Better job summary message when no common errors etc.

[FreddieAkeroyd]

If there are no common errors across jenkins system tests jobs, then the summary for system_tests_common_failures does not have an entry at that level in the console parsing although individual jobs might. This change is to make sure that the summary always has an entry at each {info,error,warning} level, but the entry may say "nothing to report". Hopefully make things clearer at standup seeing there will always be a common summary to see at each level

[rerpha]

I think we should just use the logging library rather than invent our own.

[FreddieAkeroyd]

print_message was left in by accident, it did more that just print at one point and wasn't left doing much now so i just removed it. Were you wishing to replace all uses of print() in the existing file with a call to the logging library instead?

[rerpha]

yes - the levels etc. are defined as constants already, and we dont need to worry about formatting strings etc.