Update Vue Resource

Propose updating Vue Resource.

Will require changing the way the X-CSRF-TOKEN header in bootstrap.js

This seems to be compatible with Larval Passport

resources/assets/js/bootstrap.js

@@ -26,7 +26,7 @@ require('vue-resource');
  */
 
 Vue.http.interceptors.push((request, next) => {
-    request.headers['X-CSRF-TOKEN'] = Laravel.csrfToken;
+    request.headers.set('X-CSRF-TOKEN', Laravel.csrfToken);
 
     next();
 });