fix: shows events/event dates as-is

Gatsby converts stored date to UTC cases the reported
dates shifts. This patch is to shows stored date as-is and
format date in UI side which is known as a workaround.

Fixes: aws-amplify#17
Refs: gatsbyjs/gatsby#11832 (comment)

src/graphql-fragments.js

@@ -71,7 +71,7 @@ export const SharedBetweenPostsAndEventsFragment = graphql`
     fields {
       key
       slug
-      date(formatString: "MMMM D, YYYY")
+      date
     }
     frontmatter {
       href

src/templates/Event.js

@@ -1,4 +1,5 @@
 import {graphql, Link} from 'gatsby';
+import moment from 'moment';
 import {track, extract, mapNodeToProps} from '~/utilities';
 import Img from 'gatsby-image';
 import {Text, Meta, Layout, Nav, Button} from '~/components';
@@ -182,7 +183,7 @@ export default props => {
           <div className='details'>
             <Text h2>{title}</Text>
             <div className='logistics'>
-              <Text h4 children={date} />
+              <Text h4 children={moment(date).format(`MMMM D, YYYY`)} />
               <Text h4 children=' in ' />
               <Text h4 children={join(', ', [city, country])} />
             </div>

src/utilities/groupEventEdges.js

@@ -1,4 +1,5 @@
 import {reduce, assoc, invertObj} from 'ramda';
+import moment from 'moment';
 import * as extract from './extract';
 
 export const monthNameByIndex = [
@@ -27,5 +28,6 @@ export default reduce((accumulator, current) => {
   const monthIndex = date.getMonth();
   const month = monthNameByIndex[monthIndex];
   const key = `${month} ${year}`;
+  current.node.fields.date = moment(stringifiedDate).format(`MMMM D, YYYY`);
   return assoc(key, [...(accumulator[key] || []), current], accumulator);
 }, {});