Fix: multiselect fields enable button

coscine/issues#760 coscine/issues#761

src/CreateProject.vue

@@ -368,6 +368,23 @@ export default Vue.extend({
       default: redirectToProject,
     },
   },
+  watch: {
+  	'form.Discipline': function(newVal, oldVal) {
+      if(oldVal.length > 0) {
+        this.$v.form!.Discipline!.$touch()
+      }
+    },
+  	'form.Institute': function(newVal, oldVal) {
+      if(oldVal.length > 0) {
+        this.$v.form!.Institute!.$touch()
+      }
+    },
+  	'form.Keywords': function(newVal, oldVal) {
+      if(oldVal.length > 0) {
+        this.$v.form!.Keywords!.$touch()
+      }
+    }
+  },
   methods: {
     addTag(newTag: any) {
       this.form.Keywords.push(newTag);