Draft for the gitlab docker container pull request

gitlab.yml

## Default project features settings
    default_projects_features:
      issues: {{PROJECT_DEFAULTS_ISSUES}} # can be true | false
      merge_requests: {{PROJECT_DEFAULTS_MERGE_REQUESTS}} # can be true | false
      wiki: {{PROJECT_DEFAULTS_WIKI}} # can be true | false
      wall: {{PROJECT_DEFAULTS_WALL}} # can be true | false
      snippets: {{PROJECT_DEFAULTS_SNIPPETS}} # can be true | false
      visibility_level: "{{GITLAB_PROJECTS_VISIBILITY}}"  # can be "private" | "internal" | "public"
      
  ## External issues trackers
  issues_tracker:
    redmine:
      title: "Redmine"
      ## If not nil, link 'Issues' on project page will be replaced with this
      ## Use placeholders:
      ##  :project_id        - GitLab project identifier
      ##  :issues_tracker_id - Project Name or Id in external issue tracker
      ## project_url: "http://redmine.sample/projects/:issues_tracker_id"
      project_url: "{{ISSUES_REDMINE_PROJECT_URL}}"
    
      ## If not nil, links from /#\d/ entities from commit messages will replaced with this
      ## Use placeholders:
      ##  :project_id        - GitLab project identifier
      ##  :issues_tracker_id - Project Name or Id in external issue tracker
      ##  :id                - Issue id (from commit messages)
      ## issues_url: "http://redmine.sample/issues/:id"
      issues_url: "{{ISSUES_REDMINE_ISSUES_URL}}"
    
      ## If not nil, links to creating new issues will be replaced with this
      ## Use placeholders:
      ##  :project_id        - GitLab project identifier
      ##  :issues_tracker_id - Project Name or Id in external issue tracker
      ## new_issue_url: "http://redmine.sample/projects/:issues_tracker_id/issues/new"
      new_issue_url: "{{ISSUES_REDMINE_NEW_ISSUES_URL}}"
    
    ## Gravatar
    gravatar:
      enabled: {{GRAVATAR_ENABLED}}                 # Use user avatar image from Gravatar.com (default: true)
      # gravatar urls: possible placeholders: %{hash} %{size} %{email}
      # plain_url: "http://..."     # default: http://www.gravatar.com/avatar/%{hash}?s=%{size}&d=mm
      # ssl_url:   "https://..."    # default: https://secure.gravatar.com/avatar/%{hash}?s=%{size}&d=mm
      plain_url: {{GRAVATAR_PLAIN_URL}}
      ssl_url: {{GRAVATAR_SSL_URL}}
      
    extra:
      ## Google analytics. Uncomment if you want it
      google_analytics_id: '{{GOOGLE_ANALYTICS_ID}}'

      ## Piwik analytics.
      piwik_url: '{{PIWIK_URL}}'
      piwik_site_id: '{{PIWIK_SITE_ID}}'

      ## Text under sign-in page (Markdown enabled)
      # sign_in_text: |
      #   ![Company Logo](http://www.companydomain.com/logo.png)
      #   [Learn more about CompanyName](http://www.companydomain.com/)