SPOI-2493 #resolves added hfds output operator to write data to file nam...

...e supplied in the tuple

Squashed commit of the following:

commit b37c56434e51d0ecfd71d5d53582ad720077d100
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Fri May 16 16:35:05 2014 -0700

    clean up

commit 20f341717344e617d88f745fa00c64d2465c4c95
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Thu May 15 19:23:19 2014 -0700

    added hdfs output operator to read file name from tuple and write data to that file

commit 38dbc81aa9a3e8029b99221c4f20205d653f2832
Author: Ashwin Chandra Putta <ashwin@datatorrent.com>
Date:   Thu May 15 19:21:49 2014 -0700

    abstracted out hdfs file output related common functionality