add vuex-plugin-jsdata (vuejs#479)

* add vuex-plugin-jsdata

* Update compat information

Author: AlexandreBonaventure

README.md

@@ -259,6 +259,7 @@
   - [vuex-actions ★2](https://github.com/weinot/vuex-actions) - Action utilities for vuex, supports promise-based async actions.
   - [vuex-persistedstate ★2](https://github.com/robinvdvleuten/vuex-persistedstate) - Persist and rehydrate Vuex state with localStorage support by @robinvdvleuten
   - [vue-sync](http://github.com/buhrmi/vue-sync) - Sync state with other places such as the browser URL or a backend api. directly, without using stores.
+  - [vuex-plugin-jsdata](http://github.com/AlexandreBonaventure/vuex-jsdata-plugin) - Sync state with js-data store (for Vuex 2.x).
 
 - #### Validation