refs # 6720 - necessary apidoc changes for content-management, BZ 1105276

@ehelms so
```ruby
resource_description do
  api_base_url "#{Katello.config.url_prefix}/api"
end
```

is actually running a method (right then) on the `ApiController` class. I'm not sure if that propagates down the child tree like a defined method or variable would. It's very odd that some controllers don't have to define a `api_base_url` and `/katello` is prefixed correctly, while it doesn't work for others.

I do think that this is something that needs to be looked into, but I feel that this is not an unreasonable fix at this time.