Adds router & resource.

Router DSL example: https://github.com/AgilionApps/elixir_blog_api/blob/feda3f3c934661cceb8ae955aa07fe7cbb9c6358/lib/blog/api.ex

Resource DSL example: https://github.com/AgilionApps/elixir_blog_api/blob/feda3f3c934661cceb8ae955aa07fe7cbb9c6358/lib/blog/api/v1/posts.ex
*achievable*