CBQE-0: set swappiness before installation

3.0.0-526-rel installation failed http://qa.hq.northscale.net/job/centos_x64--02_01--basic_rebalance_tests-P0/17/console

2014-03-29 05:53:19,978 - root - INFO - Warning: Swappiness is not 0.
2014-03-29 05:53:19,978 - root - ERROR - something wrong happened on 10.5.2.14!!! error:[], track_words:('warning', 'error', 'fail')
some nodes were not install successfully!

Change-Id: I082db4c60946287ff15c364981d31b89030271de
Reviewed-on: http://review.couchbase.org/35072
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>