Support nuxt store folder structure

[l2cri]

Please add store like as 'root/subStore' in nuxt.config.js I like module structure and my store have tree mode folder structure as store file/folder

//  nuxt.config.js
module.exports = {
  modules: [
    ['nuxt-vuex-localstorage', {
      localStorage: ['foo/bar', 'foo.bar'],  //  / or . as separator
      sessionStorage: ['sfoo/sbar', 'sfoo.sbar'] 
    }]
  ]
}