Fix misc stuff from lighthouse (#81)

* Fix misc stuff from lighthouse

- Icons in list were resizing to be too small.
- Added robots.txt (full exclude for now)
- Add favicon.ico placeholder
- Added page title using helmet (react-helmet + gatsby-plugin-react-helmet)
Note: not sure if react-helmet can be in dev section of package.json?

* Move helmet to header file
- Moved  `<Helmet><title>{title}</title></Helmet>` to Header.
- Added ts support for Helmet.
* Fix title header

client/gatsby-config.js

@@ -53,5 +53,6 @@ module.exports = {
         },
       },
     },
+    'gatsby-plugin-react-helmet',
   ],
 };