Changed routing framework from mux to Gin.

Swagger doc is now included in the application.
A fronted can now be hosted from the application.

cmd/frontend/src/main.js

@@ -0,0 +1,8 @@
+import Vue from 'vue'
+import App from './App.vue'
+
+Vue.config.productionTip = false
+
+new Vue({
+  render: h => h(App),
+}).$mount('#app')