Added gitlab-ci

# CI/CD:

#

# BUILD triggered by:

#  - branches

#  

#   

Build spec2md docker image:

  stage: build 

  before_script:

    - echo "$CI_JOB_TOKEN" | docker login $CI_REGISTRY -u $CI_REGISTRY_USER --password-stdin

  script: 

    - ./relaunch.sh $CI_COMMIT_BRANCH

    - docker push forge.etsi.org:5050/cti/spec2md:$CI_COMMIT_BRANCH

  after_script:

    - docker logout $CI_REGISTRY

  rules:

    - if: $CI_COMMIT_BRANCH

      changes:

        - Dockerfile

        - templates/**/*.html

        - static/**/*.css

        - static/**/*.js

        - spec2md.py

        - gridTable.py

        - web_server.py