Allow to run the Nuxeo Docker image in dev mode

Allow running the existing Nuxeo Docker image in dev mode through the NUXEO_ENVIRONMENT=dev env variable.

Running it in dev mode activate dev oriented configuration such as the org.nuxeo.dev mode, Automation chain stacktrace, ...

Following things must be validated:

• be able to register through nuxeoctl
• copy new jars and restart the server
• hot reload using the browser extension
• hot reload using nuxeo-cli if possible