perf[store]: add support to sub-modules (#2047)

Author: Yamel Senih

src/store/index.js

@@ -5,7 +5,7 @@ import getters from './getters'
 Vue.use(Vuex)
 
 // https://webpack.js.org/guides/dependency-management/#requirecontext
-const modulesFiles = require.context('./modules', false, /\.js$/)
+const modulesFiles = require.context('./modules', true, /\.js$/)
 
 // you do not need `import app from './modules/app'`
 // it will auto require all vuex module from modules file