Changed how path is created to handle Riot v2.1 api path.

Addresses #10.

I'm not a huge fan of having to pass `@region` into every single resource but I can't think of another way except to pass `self` into each one and change Base's init method to something like:

```
def initialize(api, options={})
  @faraday = api.faraday
  @region = api.region
end
```
but I'm not a fan of that either.

I already implemented a BaseV2_1 class to use with the 2.1 api methods and it works so this model is viable.  Still, not a huge fan.