Make `vue/attribute-order` rule fixable

**Tell us about your environment**

* **ESLint Version:** 4.16.0
* **eslint-plugin-vue Version:** 4.2.0
* **Node Version:** 6.9.4

**Question**

I'd like to update `vue/attribute-order`#209 so that it can be auto fixable.
Are there any concerns about this?
For example, do I need to check the side effects caused by reordering in xml attributes?
