Not compatible with webpack vue-loader v13+

[voveson]

From the release notes of vue-loader v 13.0.0:

Similarly, old CommonJS-style requires will also need to be updated:

// before
const Foo = require('./Foo.vue')

// after
const Foo = require('./Foo.vue').default

This results in the following error when using certain vue-admin components:

[Vue warn]: Failed to mount component: template or render function not defined.

I'd be happy to do a PR to bring compatibility up to date, but I'm not sure how it would affect other projects using older versions of vue-loader, or projects not using vue-loader at all. Not sure what the protocol would be for something like this...?