Merge branch 'cleanup-ci-pages' into 'master'

Cleanup CI pages

- [x] Remove `ci/projects/:id` page
- [x] Remove Continuous integration from project menu
- [x] Remove unused css/js
- [x] Remove Ci::Commit and Ci::Build controllers
- [x] Move CI services to project settings area


cc @ayufan 

Part of #2594

See merge request !1529