Improvments

Just couple thoughts.
1. Would be nice to extract (or rename existing class `Wowrb`) to let's say `Wowrb::Client`
2. `Wowrb` contains a lot of methods like

```
def method(param)
do_somethig
call_api
end
```

I'm sure it could be refactored. You can avoid calling `call_api` in each method. Just implement for example `http_get` like that:

```
def http_get(method, params)
remote_url = send method, params
call_api(remote_url)
end
```

In this case, you will be able to use this like constructions:
`http_get(:achievement, any_params)`
or
`http_get(:boss, any_params)`
etc, where the first parameter is a name of a method you want to call.

And make all methods except `http_get` private
1. It's better to make all methods as object methods instead of class