Add CORS headers

Implement versions endpoint

lib/matrix_server_web/controllers/info_controller.ex

@@ -0,0 +1,13 @@
+defmodule MatrixServerWeb.InfoController do
+  use MatrixServerWeb, :controller
+
+  @supported_versions ["r0.6.1"]
+
+  def versions(conn, _params) do
+    data = %{versions: @supported_versions}
+
+    conn
+    |> put_status(200)
+    |> json(data)
+  end
+end

lib/matrix_server_web/endpoint.ex

@@ -38,5 +38,7 @@ defmodule MatrixServerWeb.Endpoint do
   plug Plug.MethodOverride
   plug Plug.Head
   plug Plug.Session, @session_options
+  plug CORSPlug
+
   plug MatrixServerWeb.Router
 end

lib/matrix_server_web/router.ex

@@ -12,5 +12,7 @@ defmodule MatrixServerWeb.Router do
       post "/register", AccountController, :register
       get "/register/available", AccountController, :available
     end
+
+    get "/client/versions", InfoController, :versions
   end
 end