Add healthcheck route

lib/tusker_push_web/controllers/healthcheck_controller.ex

@@ -0,0 +1,7 @@
+defmodule TuskerPushWeb.HealthcheckController do
+  use TuskerPushWeb, :controller
+
+  def healthcheck(conn, _params) do
+    send_resp(conn, 200, "ok")
+  end
+end

lib/tusker_push_web/router.ex

@@ -5,6 +5,10 @@ defmodule TuskerPushWeb.Router do
     plug :accepts, ["json"]
   end
 
+  scope "/", TuskerPushWeb do
+    get "/healthcheck", HealthcheckController, :healthcheck
+  end
+
   scope "/push", TuskerPushWeb do
     pipe_through :api