Fix for NPE on older Hadoop APIs

Author: childsb

src/main/java/org/apache/hadoop/fs/glusterfs/GlusterVolume.java

@@ -69,7 +69,10 @@ public GlusterVolume(Configuration conf){
         this.setConf(conf);
     }
 
-    public URI getUri() { return NAME; }
+    public URI getUri() { 
+      if(NAME==null) return URI.create("glusterfs:///");
+      return NAME;       
+   }
 
     public void initialize(URI uri, Configuration conf) throws IOException {
         /* we only really care about the URI up to the path, so strip other things off */