certain require do not load extension Service class

```
$ bin/jruby -e "require 'uri:classloader:/lib/ruby/shared/json/ext/parser'; p JSON::Ext::Parser"
```

fails. same with the _file:_, _jar:_, _file:jar:_ protocol. the *uri:jar:file:my.jar!/" protocol does not even look into the right place place to load the Service class from the gem extension.
