FEATURE: custom setting for large square site icon

This icon is used for android splash screen

spec/controllers/metadata_controller_spec.rb

@@ -3,11 +3,17 @@ require 'rails_helper'
 RSpec.describe MetadataController do
   describe 'manifest.json' do
     it 'returns the right output' do
+
       title = 'MyApp'
       SiteSetting.title = title
+      SiteSetting.large_icon_url = "http://big.square/png"
+
       get :manifest
-      expect(response.body).to include(title)
       expect(response.content_type).to eq('application/json')
+      manifest = JSON.parse(response.body)
+
+      expect(manifest["name"]).to eq(title)
+      expect(manifest["icons"].first["src"]).to eq("http://big.square/png")
     end
   end