Merge branch 'dev-proxy-favicon' into 'develop'

Webpack: proxy `favicon.png` to the backend in devServer

See merge request soapbox-pub/soapbox-fe!630

webpack/development.js

@@ -23,6 +23,7 @@ const backendEndpoints = [
   '/static',
   '/main/ostatus',
   '/ostatus_subscribe',
+  '/favicon.png',
 ];
 
 const makeProxyConfig = () => {