Don't attach logs for successful builds and archive the logs for the rest

This is for issue #52 
Right now I see a problem here. tps.log seems to only contain the results of the tests, but not if something was broken in setting up the environment etc. For that case also build.log is attached, what I have seen right now. So what is the exact difference between those two attached files. And do we really need both, or can we get rid of one of those?