Setup basic Plug.Router framework for serving requests

Rather than use a full blown framework*, adding basic routing with
Plug.Router seems to make more sense, since I'm not planning on hosting
any content through this app. The app itself will just be endpoints for
all available services that redirect the user to an available instance
for the requested service.

Note that I might change my mind about this, but that's unlikely. At
most there would just be a home page with info about available
instances, but even then that seems kinda pointless. Trying to keep this
as absolutely simple as possible.

*like Phoenix

lib/privacy_revolver.ex

@@ -0,0 +1,18 @@
+defmodule PrivacyRevolver do
+  @moduledoc """
+  Documentation for `PrivacyRevolver`.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> PrivacyRevolver.hello()
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end

lib/privacy_revolver/application.ex

@@ -0,0 +1,15 @@
+defmodule PrivacyRevolver.Application do
+  @moduledoc false
+
+  use Application
+
+  @impl true
+  def start(_type, _args) do
+    children = [
+      Plug.Cowboy.child_spec(scheme: :http, plug: PrivacyRevolver.Router, options: [port: 4001])
+    ]
+
+    opts = [strategy: :one_for_one, name: PrivacyRevolver.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end

lib/privacy_revolver/router.ex

@@ -0,0 +1,10 @@
+defmodule PrivacyRevolver.Router do
+  use Plug.Router
+
+  plug :match
+  plug :dispatch
+
+  get "/ping" do
+    send_resp(conn, 200, "pong")
+  end
+end