Allow for using build UUID as temp job dir name

This lets us use the build UUID as the job temp dir name
so that the finger log streamer can search the job root dir
to find the requested log by build ID.

Also, since the JobDir parameters aren't really optional, just
make that explicit.

Change-Id: Ifeb9f37c6c9c1ce792079e63a6c507461081f03c
1 file changed