PipeMapRed.java has uninitialized members log_ and LOGNAME

PipeMapRed.java has members log_ and LOGNAME, which are never initialized and they are used in code for logging in several places.
They should be removed and PipeMapRed should use commons LogFactory and Log for logging. This would improve code maintainability.

Also, as per comment , stream.joblog_ configuration property can be removed.