Add CNWAN Reader initial code (CloudNativeSDWAN#1)

This commit introduces all files that make CNWAN Reader work.

Files include packages, OpenAPI generated client code, Dockerfile and
more.

Readme is updated accordingly with instructions on how to configure
and run the program.

Signed-off-by: Elis Lulja <elulja@cisco.com>

Author: asimpleidea

.gitignore

@@ -0,0 +1,3 @@
+.DS_Store
+cnwan-reader
+credentials/

COPYRIGHT

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+Copyright 2020 Cisco
+
+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.