Implement increment() method in CountMetric class. (apache#537)

Abstract method increaseCount() in CountMetric is a generic method used in inherited classes. We should implement this method in CountMetric to reduce duplicate code in inherited classes.
Change list:
1. Move increaseCount() to CountMetric.
2. Change the name to increment() and implement the method.

Author: huizhilu

helix-core/src/main/java/org/apache/helix/controller/rebalancer/waged/WagedRebalancer.java

@@ -185,7 +185,7 @@ public Map<String, IdealState> computeNewIdealStates(ResourceControllerDataProvi
       CountMetric rebalanceFailureCount = _metricCollector.getMetric(
           WagedRebalancerMetricCollector.WagedRebalancerMetricNames.RebalanceFailureCounter.name(),
           CountMetric.class);
-      rebalanceFailureCount.increaseCount(1L);
+      rebalanceFailureCount.increment(1L);
 
       HelixRebalanceException.Type failureType = ex.getFailureType();
       if (failureType.equals(HelixRebalanceException.Type.INVALID_REBALANCER_STATUS) || failureType
@@ -332,7 +332,7 @@ private void refreshBaseline(ResourceControllerDataProvider clusterData,
     CountMetric globalBaselineCalcCounter = _metricCollector.getMetric(
         WagedRebalancerMetricCollector.WagedRebalancerMetricNames.GlobalBaselineCalcCounter.name(),
         CountMetric.class);
-    globalBaselineCalcCounter.increaseCount(1L);
+    globalBaselineCalcCounter.increment(1L);
 
     LatencyMetric globalBaselineCalcLatency = _metricCollector.getMetric(
         WagedRebalancerMetricCollector.WagedRebalancerMetricNames.GlobalBaselineCalcLatencyGauge
@@ -379,7 +379,7 @@ private Map<String, ResourceAssignment> partialRebalance(
     CountMetric partialRebalanceCounter = _metricCollector.getMetric(
         WagedRebalancerMetricCollector.WagedRebalancerMetricNames.PartialRebalanceCounter.name(),
         CountMetric.class);
-    partialRebalanceCounter.increaseCount(1L);
+    partialRebalanceCounter.increment(1L);
 
     LatencyMetric partialRebalanceLatency = _metricCollector.getMetric(
         WagedRebalancerMetricCollector.WagedRebalancerMetricNames.PartialRebalanceLatencyGauge

helix-core/src/main/java/org/apache/helix/monitoring/metrics/implementation/RebalanceCounter.java

@@ -27,15 +27,10 @@
  */
 public class RebalanceCounter extends CountMetric {
   /**
-   * Instantiates a new count metric.
+   * Instantiates a new rebalance count metric.
    * @param metricName the metric name
    */
   public RebalanceCounter(String metricName) {
     super(metricName, 0L);
   }
-
-  @Override
-  public void increaseCount(long count) {
-    updateValue(getValue() + count);
-  }
 }

helix-core/src/main/java/org/apache/helix/monitoring/metrics/implementation/RebalanceFailureCount.java

@@ -1,7 +1,27 @@
 package org.apache.helix.monitoring.metrics.implementation;
 
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
 import org.apache.helix.monitoring.metrics.model.CountMetric;
 
+
 public class RebalanceFailureCount extends CountMetric {
   /**
    * Instantiates a new Simple dynamic metric.
@@ -11,9 +31,4 @@ public class RebalanceFailureCount extends CountMetric {
   public RebalanceFailureCount(String metricName) {
     super(metricName, 0L);
   }
-
-  @Override
-  public void increaseCount(long count) {
-    updateValue(getValue() + count);
-  }
 }

helix-core/src/main/java/org/apache/helix/monitoring/metrics/model/CountMetric.java

@@ -43,7 +43,9 @@ public CountMetric(String metricName, long initCount) {
    *
    * @param count
    */
-  public abstract void increaseCount(long count);
+  public void increment(long count) {
+    updateValue(getValue() + count);
+  }
 
   @Override
   public String getMetricName() {