Add CORS_ENABLED env var for docker-compose

[pasquy73]

Added the CORS_ENABLED environment variable as described in the issue 608.
Please, check where it is necessary to update the doc (i.e. https://github.com/telefonicaid/fiware-sth-comet/blob/master/doc/manuals/running.md) to add this new env var.
A usage can be:

  sth-comet:
    image: fiware/sth-comet:${STH_COMET_VERSION}
    hostname: sth-comet
    container_name: fiware-sth-comet
    restart: always
    depends_on:
      - database-mongo
    networks:
      - monitoring-net
    ports:
      - ${STH_COMET_PORT}:${STH_COMET_PORT}
    environment:
      - STH_HOST=0.0.0.0
      - STH_PORT=${STH_COMET_PORT}
      - DB_PREFIX=sth_
      - DB_URI=database-mongo:${MONGO_DB_PORT}
      - LOGOPS_LEVEL=INFO
      - CORS_ENABLED=true

I don't know if it can be included in the test scripts, I only changed the sthConfiguration.js file in the lib/configuration folder.

[fgalan]

Thank for the contribution!

In order to complete the PR, please take into account the following feedback:

• Please add an entry to CHANGES_NEXT_RELEASE (future changelog) to briefly describe the modification done by this PR
• The new functionality should be described in documentation. Please have a look to existing documents in doc/ and modify the relevants .md files.

[pasquy73]

I added the entry regarding CORS_ENABLED in the CHANGES_NEXT_RELEASE. I also added a new line in the running.md (line 104) to define the CORS_ENABLED attribute.
Please note that inside the Cors configuration, there are other attributes that can be overwritten (i.e. origin, headers, etc.) when you enable Cors, but we can add them in the next releases.

[fgalan]

Suggested change

	- Add: CORS_ENABLED env var (boolean) to enable the cors configuration (of config.js file) in your docker image (#608)
	- Add: CORS_ENABLED env var (boolean) to enable the cors configuration (of config.js file) in your docker image (#608)
	- Set Nodejs 14 as minimum version in packages.json (effectively removing Nodev12 from supported versions)

This seems to be a wrongly solved merge conflict. You shouldn't delete existing lines in CHANGES_NEXT_RELEASE file, just add yours.

[pasquy73]

Sorry, I didn't know! I added the first line in CHANGES_NEXT_RELEASE

[fgalan]

LGTM. Thanks!