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.

Groups can enable/disable LFS, but this setting can be overridden at the project level. Admin only

This reverts commit bf2a86b7.

This reverts commit 68155ee7, reversing
changes made to 7ebd011e.

And create new Project#requesters, Group#requesters scopes.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Also, reuse partials from the non-admin views.

Signed-off-by: Rémy Coutable <remy@rymai.me>

This reverts commit 13e37a3e.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Closes #5908

Make the following changes to deal with new behavior in Rails 4.1.2:

* Use nested resources to avoid slashes in arguments to path helpers.