MLHR-1160 #resolves created hdfs output operator with exactly once semantics

Squashed commit of the following:

commit 33efaf4e3f17af98f081cb56982d62931d007efa
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri Jun 13 11:40:07 2014 -0700

    added test cases

commit 5f17496375d8dbcb6c83ad463ea4a0cb77015f24
Merge: 8fb67c0 dd1cb62
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Thu Jun 12 18:18:19 2014 -0700

    Merge branch 'master' of https://github.com/DataTorrent/Malhar into MLHR-1160_wip

commit 8fb67c028ad29ad56c0ce03a37ce1bf89cba009b
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Thu Jun 5 22:55:13 2014 -0700

    added hdfs exactly once output operator