Added Apache2 Copyright Header

src/main/java/io/github/robwin/markup/builder/Markup.java

@@ -1,3 +1,21 @@
+/*
+ *
+ *  Copyright 2015 Robert Winkler
+ *
+ *  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 io.github.robwin.markup.builder;
 
 /**