Adds scope+namespace support for APIs mounted inside Phoenix

[adamstrickland]

Found that using Maru APIs forwarded to by the Phoenix router would get confused when nested inside scope and (or?) namespace clauses. This PR fixes that.

---

Example problem:

Assume the router.ex:

scope "/api" do
  pipe_through :api

  scope "/mob" do
    forward "/v1", Foo.Apis.Mobile.V1
  end
end

and the API, in /web/apis/mobile/v1.ex:

defmodule Foo.Apis.Mobile.V1 do
  use Maru.Router

  namespace "/bars" do
    get "/", do: conn |> json %{status: "OK"}
  end
end

In this case, the router would not properly put together both the scope and namespace path components. In the above example, the proper, fully-qualified path should be /api/mob/v1/bars, but Maru.Builder.Routers.generate was only producing /bars.

[falood]

Thank you for point it out. I'm thinking this issue these days, and it seems that this PR will NOT solve your problem. This PR requires an argument mount_path and I think this would be read from phoenix routers. I notified that there's to print maru routes forwarded by phoenix router, and I'll do it soon. So, I'll close this PR without merge and improve a way to show maru routes within phoenix, do you think it's feasible?

[adamstrickland]

Yes, sounds good. Thanks.

[falood]

I've push new task maru.routes to master and new version will be release soon.