Add api points for ci cd status. Add favicon.

app/controllers/projects/builds_controller.rb

app/controllers/projects/merge_requests_controller.rb

app/controllers/projects/pipelines_controller.rb

app/serializers/build_entity.rb

app/serializers/build_serializer.rb

app/serializers/status_entity.rb

config/routes/project.rb

lib/gitlab/ci/status/build/failed_allowed.rb

lib/gitlab/ci/status/canceled.rb

lib/gitlab/ci/status/created.rb

lib/gitlab/ci/status/failed.rb

lib/gitlab/ci/status/pending.rb

lib/gitlab/ci/status/running.rb

lib/gitlab/ci/status/skipped.rb

lib/gitlab/ci/status/success.rb

lib/gitlab/ci/status/success_warning.rb