Add "-" to project wildcard routes

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

lib/gitlab/path_regex.rb

@@ -80,6 +80,7 @@ module Gitlab
     # By rejecting `badges` the router can _count_ on the fact that `badges` will
     # be preceded by the `namespace/project`.
     PROJECT_WILDCARD_ROUTES = %w[
+      -
       badges
       blame
       blob