Merge branch 'sh-add-missing-foreign-key-import-export-uploads' into 'master'

Add missing foreign key in import_export_uploads

See merge request gitlab-org/gitlab-ce!20458

db/schema.rb

@@ -2262,6 +2262,7 @@ ActiveRecord::Schema.define(version: 20180702120647) do
   add_foreign_key "gpg_signatures", "gpg_keys", on_delete: :nullify
   add_foreign_key "gpg_signatures", "projects", on_delete: :cascade
   add_foreign_key "group_custom_attributes", "namespaces", column: "group_id", on_delete: :cascade
+  add_foreign_key "import_export_uploads", "projects", on_delete: :cascade
   add_foreign_key "internal_ids", "namespaces", name: "fk_162941d509", on_delete: :cascade
   add_foreign_key "internal_ids", "projects", on_delete: :cascade
   add_foreign_key "issue_assignees", "issues", name: "fk_b7d881734a", on_delete: :cascade