Adding keys in store/index will overwrite default store

[NickBolles]

When using the example located here:
https://github.com/gustojs/nuxt-feathers-vuex#vuex-store

the actions: {} key will overwrite the defaults store actions key, which has nuxtServerInit on it, which in turn initialized the authentication. I just spent a few hours debugging this and finally figured out the issue.

At the very least this should be called out in the documentation, but I think a better solution is to use a deep merge in createStore instead of Object.assign.