This solves https://dev.gitlab.org/gitlab/gitlabhq/issues/2646
1. This MR simplifies CI permission model:
- read_build: allows to read a list of builds, artifacts and trace
- update_build: allows to cancel and retry builds
- admin_build: allows to manage triggers, runners and variables
- read_commit_status: allows to read a list of commit statuses (including the status of a build, but doesn't allow to see a build details)
- create_commit_status: allows to create a new commit status using API
2. I do make sure that the proper permissions are used in all places where the CI can be shown.
3. Add the `read_build` ability if user is anonymous or guest and allow_guest_to_access_builds is enabled.
4. Add CI setting: public_builds.
5. The artifacts specific permission are removed, since they are covered by `*_build`.
Automatically fork a project when not allowed to edit a file.
Fixes#3215.
To do:
- [ ] Add tests
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## "Edit" button on file in a project the user does NOT have write access to

## Clicking will automatically create a fork

## When the fork has been created, the user is returned to the edit page on the original project with a notice

## The user cannot change the target branch and is informed that editing will start an MR

## Hitting "Commit changes" will commit and start an MR from my fork to the origin project

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## "Create file, "Upload file" and "New directory" buttons in a project the user does NOT have write access to

## Clicking any of these options will automatically create a fork

## When the fork has been created, the user is returned to the tree page on the original project with a notice

## Clicking "New directory" again will show the modal. The user cannot change the target branch and is informed that editing will start an MR

## Hitting "Create directory" will commit and start an MR from my fork to the origin project

cc @dzaporozhets @skyruler
See merge request !2145
Ci Project migrate
- This doesn't migrate: allow_git_fetch, coverage_regex, timeout. Since this are project configuration settings I would propose to migrate them to `.gitlab-ci.yml`.
- This requires offline migrations.
- It simplifies database models making all CI objects to be attached to: Project.
- It removes Ci::Project, but makes /ci/projects working by adding method: Project.find_by_ci_id for backward compatibility (badges, triggers).
- We should add default `timeout` to Application Settings.
- It misses specs.
- It is based on ci-services-migrate for now.
- It removes CI events.
- It removes administrator CI projects overview.
- It removes CI application settings.
In 8.4 or 8.5 we can remove redundant tables and columns.
See merge request !1987