Fix for Bug #1373530. Zookeeper quorum was wrong in dcs-site.xml file.

The dcs_installer script was incorrectly trying to get the zookeeper
quorum node name in the single node cluster case.  In the single
node cluster case the zookeeper quorum is simply the node name.

Change-Id: I69b7f857521ac9fd03fdd63742b6bdbf94ee3c6b
Merge "Fix for Bug #1373530. Zookeeper quorum was wrong in dcs-site.xml file."