fix: using master branch for kafka-contrib

Default attribute in kafka cookbook had been temporarily
changed to use 'zarkotest'; this reverts that change
and uses the master branch by default.

Squashed commit of the following:

commit bf59229aee6ec9d7b8eed2d95d1e1dc575ab077f
Author: Eric Katerman <eric@infochimps.com>
Date:   Wed Mar 19 17:04:53 2014 -0700

    using master branch for kafka-contrib

    Change-Id: Ib0a1fd687b00ac980e1a68bfb1fb28bdb59c58f4

Change-Id: I09137c101cf8fa2e02c424c4097c54763ca08d15