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/src/pages/index.tsx

@@ -41,7 +41,6 @@ const IndexPage = () => {
 
   return (
     <Layout>
-
       <main id="main-content" role="main">
         <section className="grid-container">
           <div className="grid-row grid-gap">