Add license details for Gradle wrapper

gradlew.bat

@@ -3,6 +3,20 @@
 @rem
 @rem  Gradle startup script for Windows
 @rem
+@rem  Copyright 2017 the original author or authors.
+@rem
+@rem  Licensed under the Apache License, Version 2.0 (the "License");
+@rem  you may not use this file except in compliance with the License.
+@rem  You may obtain a copy of the License at
+@rem
+@rem      http://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem  Unless required by applicable law or agreed to in writing, software
+@rem  distributed under the License is distributed on an "AS IS" BASIS,
+@rem  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem  See the License for the specific language governing permissions and
+@rem  limitations under the License.
+@rem
 @rem ##########################################################################
 
 @rem Set local scope for the variables with windows NT shell