Addresses part of #16, (#71)

Integrate gatsby-plugin-intl for internationalization
Replaces static text with `intl.formatMessage` call and Links with `gatsby-plugin-intl` equivalent
Note: `npm install` now requires `--force` to install the latest `gatsby-plugin-intl` as it doesn't explicitly support gatsby3.0

client/gatsby-config.js

@@ -12,14 +12,29 @@ module.exports = {
   siteMetadata: {
     title: "Justice40",
   },
-  plugins: [{
-    resolve: 'gatsby-plugin-sass',
-    options: {
-      cssLoaderOptions: {
-        modules: {
-          exportLocalsConvention: 'camelCaseOnly'
+  plugins: [
+    {
+      resolve: 'gatsby-plugin-sass',
+      options: {
+        cssLoaderOptions: {
+          modules: {
+            exportLocalsConvention: 'camelCaseOnly'
+          }
         }
       }
-    }
-},],
+    },
+    {
+        resolve: `gatsby-plugin-intl`,
+        options: {
+          // language JSON resource path
+          path: `${__dirname}/src/intl`,
+          // supported language
+          languages: [`en`, `es`],
+          // language file path
+          defaultLanguage: `en`,
+          // option to redirect to `/en` when connecting `/`
+          redirect: true,
+        },
+    },
+  ],
 };