Removes redundant struct

This is a totally stupid PR but I'll send it because I was going to add going to add a feature to `CLI.add` to allow multiple additions but then I regret it :P 

Using `class Something < Struct.new(:a)` generates a useless instance of which the class inherits. It can be called `Something = Struct.new(:a)`

```ruby
class A < Struct.new(:a)
end

B = Struct.new(:b)

A.ancestors
# => [A, #<Class:0x007fbee3027908>, Struct, Enumerable, Object, Kernel, BasicObject]

B.ancestors
# => [B, Struct, Enumerable, Object, Kernel, BasicObject]
```

Again, this is probably stupid but I enjoy reading your code.