slug: move slug check to beforeUpdate

Fixes #12

frontend/src/components/MainEditor.vue

@@ -27,10 +27,14 @@
       slug: String
     },
     created() {
+      this.save = _.debounce(this.save, 2000)
+    },
+    beforeUpdate() {
+      console.log('checking for slug: '+this.$props.slug)
       if (this.$props.slug) {
+        console.log('found slug: '+this.$props.slug)
         this.getFile(this.$props.slug)
       }
-      this.save = _.debounce(this.save, 2000)
     },
     computed: {
       tags: function () {