Async css load, disable service worker, link preconnect, responsive images

• remove '+' '=' and ',' from the hash generation alphabet
• Add responsive image support
• Disabling service worker will actually uninstall it
• Server Timing Header see here
• automatic preconnect < link > added, web fonts preload moved closer to < head > for faster font load
• Add < link > with < noscript > when async css loading is enabled. without javascript, stylesheet were not previously rendered