specs for user model

small specs for user model in the application
If you add specs which you can't yet implement, but still want to keep it as a reminder you can/should use `pending`.
That way it will appear as pending when you run the specs and will not be forgotten.

You can find more on `pending` [here](https://relishapp.com/rspec/rspec-core/docs/pending-and-skipped-examples/pending-examples)