added gzip and bzip2 support for local (non-hadoop) dumbo job

I added gzip and bzip2 file support for mapper input.

The current dumbo seems only support this kind of mapreduce in local mode.
`cat input | mapper | sort | reducer > output`

What I added works like this.
`zcat input | mapper | sort | reducer > output`
`bzcat input | mapper | sort | reducer > output`