Merge branch '30272-bvl-reject-more-namespaces' into 'master'

app/models/concerns/cache_markdown_field.rb

app/models/namespace.rb

app/models/project.rb

app/models/user.rb

app/validators/dynamic_path_validator.rb

app/validators/namespace_validator.rb

app/validators/project_path_validator.rb

changelogs/unreleased/30272-bvl-reject-more-namespaces.yml

...t_migrate/20170412174900_rename_reserved_dynamic_paths.rb

doc/development/migration_style_guide.md

lib/constraints/group_url_constrainer.rb

lib/constraints/project_url_constrainer.rb

lib/gitlab/database/migration_helpers.rb

lib/gitlab/database/rename_reserved_paths_migration/v1.rb

...e/rename_reserved_paths_migration/v1/migration_classes.rb

...atabase/rename_reserved_paths_migration/v1/rename_base.rb

...e/rename_reserved_paths_migration/v1/rename_namespaces.rb

...ase/rename_reserved_paths_migration/v1/rename_projects.rb

lib/gitlab/etag_caching/router.rb

lib/gitlab/regex.rb