Added copyright notes

Author: Andriy.Lishchynskyi

tools/export/cdt/__init__.py

@@ -1,3 +1,19 @@
+"""
+mbed SDK
+Copyright (c) 2016-2019 ARM Limited
+
+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.
+"""
 import re
 import os
 import json