Fix for string problem from #7

Hello! Here is  new requirements for sidekiq to include 2.13 version and fix for #11 made by @springbok for that error:

```
2013-08-29T09:45:51Z 10358 TID-sq27c ERROR: comparison of String with Module failed
2013-08-29T09:45:51Z 10358 TID-sq27c ERROR: sidekiq_status-92654988ee87/lib/sidekiq_status/client_middleware.rb:6:in `<'
```

I need this fixes but I have no idea about fixes for template rendering (other commits in #7).