Project Settings Templates

This idea began as a comment on a different issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/3785#note_3326101

There should be the ability to set up a GitLab project template - not related to files or folder structure, but a template for the actual project settings inside GitLab, from default branch structure, protected branch settings, default labels, maybe even a default wiki page (in case there's a particular format an organization uses).

The folder and file structure should be left up to the organization, who can use any number of project template generators to accomplish that task. But organizations will generally use the same branch structure and labels for all projects.

This would be very helpful for my organization where we follow a Gitlab Flow-like pattern, with protected master and production branches. Every new repository requires us to create and push a production branch, then go to project settings and set the production branch to protected. Then we need to generate the default set of labels, remove a few and edit a few others. We don't typically use the wiki, but when we do, we paste in a default template and edit it. If some of these steps are forgotten in the beginning, it can cause trouble down the line (pushing to the production branch?!).