Add Apache 2.0 License

[dgarros]

Environment

• DSync version: master

Proposed Functionality

Before making this repo public we need to add a license at the root of the repo and at the top of each file.

I've been using this one for the onboarding plugin

Copyright 2020 Network to Code <info@networktocode.com>
Network to Code, LLC

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.