Aes/entity tests

I don't think you need the redundancy here. I don't pay much attention to the use of `Given` or `When`--I'd rather make the scenarios readable. So I'd probably word it like this:

```cucumber
When a [note "a" instead of "the"] shared habit is converted to a private habit
Then the system should keep the shared habit
And the system should create a new private habit
```

However, I think there's a problem here. A fundamental characteristic of a private habit is that it's specific to a single user. So maybe this needs a bit more clarification:

```cucumber
When a habit is shared by a few users
And one of the user makes that habit private
Then the system should remove that user from the shared habit
And it should attach the user to a new habit
And it should make the new habit private to that one user
And it should copy all other relevant characteristics [which?] from the first habit to the new one
And it should keep all the other users sharing the first habit
```

I believe this specifies the behavior clearly and unambiguously, and exclusively in terms of the domain.