Add shield, only build master

Author: PatrickSachs

.travis.yml

@@ -12,4 +12,7 @@ deploy:
   github-token: $GITHUB_TOKEN
   keep-history: true
   on:
-    branch: master
+    branch: master
+branches:
+  only:
+  - master

README.md

@@ -1,5 +1,7 @@
 # slow-tree
 
+[![Build Status](https://travis-ci.com/PatrickSachs/slow-tree.svg?branch=master)](https://travis-ci.com/PatrickSachs/slow-tree)
+
 A web based 2D-tree creation application. Check it out at [tree.sahnee.de](https://tree.sahnee.de/)!
 
 ![Game Screenshot](https://data.patrick-sachs.de/content/slow-tree/github-banner.png)

webpack.config.js

@@ -15,7 +15,7 @@ dotenv.config({ path: ".env.local" });
 dotenv.config({ path: isProduction ? ".env.prod" : ".env.dev" });
 dotenv.config({ path: ".env" });
 
-console.log("Enviroment variables are:", {
+console.log("Environment variables are:", {
   NODE_ENV: process.env.NODE_ENV,
   SERVICE_WORKER: process.env.SERVICE_WORKER,
   BROWSERSYNC: process.env.BROWSERSYNC