libhdfs++: Incorrect parse of URIs from hdfs-site.xml

It looks like the URI class confuses the host and scheme if the original URI didn't have a scheme.

Example from hdfs-site.xml. Config generated using the cloudera MC.

    <name>dfs.namenode.servicerpc-address.nameservice1.namenode86</name>
    <value>this-is-node-01.duder.com:8022</value>

host = empty string
port = unset optional
scheme = this-is-node-01.duder.com