Merge branch 'remove_external_trackers_from_yml' into 'master'

We've moved external trackers to service, remove from gitlab.yml.

Fixes #1937

See merge request !1743

config/gitlab.yml.example

@@ -86,35 +86,6 @@ production: &base
     # The default is 'tmp/repositories' relative to the root of the Rails app.
     # repository_downloads_path: tmp/repositories
 
-  ## 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"
-    #
-    #   ## 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"
-    #
-    #   ## 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"
-    #
-    # jira:
-    #   title: "Atlassian Jira"
-    #   project_url: "http://jira.sample/issues/?jql=project=:issues_tracker_id"
-    #   issues_url: "http://jira.sample/browse/:id"
-    #   new_issue_url: "http://jira.sample/secure/CreateIssue.jspa"
-
   ## Gravatar
   ## For Libravatar see: http://doc.gitlab.com/ce/customization/libravatar.html
   gravatar: