Clean up well-known routes/controllers (#1649)

* Add request spec for host meta route returning xml

* Add routing spec for xrd routes

* Update well-known routes

* Move webfinger and host-meta actions to their own controllers

spec/controllers/well_known/host_meta_controller_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+describe WellKnown::HostMetaController, type: :controller do
+  render_views
+
+  describe 'GET #show' do
+    it 'returns http success' do
+      get :show, format: :xml
+
+      expect(response).to have_http_status(:success)
+    end
+  end
+end