Update storage-only test runner to Mocha
Update storage-only test runner to Mocha

Change-Id: I9d75a314801ce0b1a883124cce9e573da59340a0

agektmr/pwa-ecommerce-demo,agektmr/pwa-ecommerce-demo,google-developer-training/pwa-ecommerce-demo,google-developer-training/pwa-ecommerce-demo