MB-100: do not use domain names for installation

this might cause problems for ec2 instances.

while it saves the fussy hostname/ip interleaving issue.

Change-Id: Ieb4126becac28c87eaeab7661a6496155debccb8
Reviewed-on: http://review.couchbase.org/28683
Reviewed-by: Ronnie Sun <ronnie@couchbase.com>
Tested-by: Ronnie Sun <ronnie@couchbase.com>