Implementing configurable CORS settings

[ash0ne]

Was using docker-http-https-echo to test a frontend app and thought it'd be useful to have a way to specify the CORS policy through config like so.

docker run -d -e CORS_ALLOW_ORIGIN="http://localhost.4000" -e CORS_ALLOW_HEADERS="x-custom-test-header"

Changes

• Updates to index.js to implement configurable CORS settings for HTTP echo server
• Updates to README to document the env vars that needed to be updated for setting the CORS policy
• Added tests in tests.sh

[mendhak]

Nice one, thanks. I'll release it in due CORS 😆

[mendhak]

:33 is released in Docker Hub and Github Registry.