docs: add proper license to ThreadCPUTimeTracker

Author: PtrMan

src/main/java/ptrman/meter/resource/ThreadCPUTimeTracker.java

@@ -1,6 +1,19 @@
+/* Copyright 2009 - 2010 The Stajistics Project
+ *
+ * Licensed 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.
+ */
 package ptrman.meter.resource;
 
-
 import ptrman.meter.event.DoubleMeter;
 
 import java.lang.management.ManagementFactory;