Fix task timings
Fix task timings

I noticed that the reports generated when using sbt.task.timings=true
made very little sense. They were displaying timings for tests that
couldn't possibly have been run. I tracked this down to the TaskTimings
be stored in the progressReport setting which meant they were reused
across multiple task runs. After this change, the reports made a lot
more sense.

xuwei-k/xsbt,sbt/sbt,sbt/sbt,mdedetrich/sbt,mdedetrich/sbt,mdedetrich/sbt,xuwei-k/xsbt,xuwei-k/xsbt,sbt/sbt,mdedetrich/sbt,mdedetrich/sbt,sbt/sbt,mdedetrich/sbt,sbt/sbt,xuwei-k/xsbt,mdedetrich/sbt,sbt/sbt,sbt/sbt,xuwei-k/xsbt