buildTransportClient() - Properly handle case in which only a single Ela...

...sticSearch host has been configured.

If only a single ElasticSearch host has been configured, it can result in: 'SEVERE: Execution aborted.
org.elasticsearch.client.transport.NoNodeAvailableException: No node available'

This simple fix ensures that configuring a single ElasticSearch host doesn't yield the aforementioned error.