Not only tracking auto-cancelling in pipelines,
we'll also track this in jobs because pipelines
could be retried and the information would get lost
when this happened. Also erase auto-cancelling
relation for pipelines when they're retried.

We can't properly use foreign keys on columns that are configured for
polymorphic associations which has disadvantages related to data
integrity and storage. Given we only use time tracking for Issues and
Merge Requests we're moving to the usage of regular associations.

Apply the same spam checks to public snippets (either personal snippets
that are public, or public snippets on public projects) as to issues on
public projects.

This adds counters for build artifacts and LFS objects, and moves
the preexisting repository_size and commit_count from the projects
table into a new project_statistics table.

The counters are displayed in the administration area for projects
and groups, and also available through the API for admins (on */all)
and normal users (on */owned)

The statistics are updated through ProjectCacheWorker, which can now
do more granular updates with the new :statistics argument.

* add parent_id field to namespaces table to store relation with nested groups
* create routes table to keep information about full path of every group and project
* project/group lookup by full path from routes table
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixed all related specs and also changed the logic to handle edge cases. This includes exporting and exporting of group labels, which will get associated with the new group (if any) or they will become normal project labels otherwise.

Found other issues to do with not being able to import all labels at once in the beginning of the JSON - code was much simpler when we import all labels and milestones associated to a project first, then the associations will find the already created labels instead of creating them from the associations themselves.

https://gitlab.com/gitlab-org/gitlab-ce/builds/4710913