Show the version of the current build, distinguishing between

development and production builds. The layout needs to be refined, it's
still quite ugly as of now.

src/environments/environment.prod.ts

@@ -1,3 +1,4 @@
 export const environment = {
-  production: true
+  production: true,
+  appVersion: require('../../package.json').version
 };

src/environments/environment.ts

@@ -3,7 +3,8 @@
 // The list of file replacements can be found in `angular.json`.
 
 export const environment = {
-  production: false
+  production: false,
+  appVersion: `${require('../../package.json').version} (development build)`
 };
 
 /*