add missing getters to FsInfo.IoStats class

Without the getters there is no way to retrieve the values for its instance members from the java api, they only get printed out on the REST layer

core/src/main/java/org/elasticsearch/monitor/fs/FsInfo.java

@@ -386,6 +386,30 @@ public class FsInfo implements Iterable<FsInfo.Path>, Writeable, ToXContent {
             out.writeLong(totalWriteKilobytes);
         }
 
+        public DeviceStats[] getDevicesStats() {
+            return devicesStats;
+        }
+
+        public long getTotalOperations() {
+            return totalOperations;
+        }
+
+        public long getTotalReadOperations() {
+            return totalReadOperations;
+        }
+
+        public long getTotalWriteOperations() {
+            return totalWriteOperations;
+        }
+
+        public long getTotalReadKilobytes() {
+            return totalReadKilobytes;
+        }
+
+        public long getTotalWriteKilobytes() {
+            return totalWriteKilobytes;
+        }
+
         @Override
         public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
             if (devicesStats.length > 0) {