Add selfie and user1 and user2 identical chekcs to does_follow command.

Add two checks to `does_follow`.

Before:

```
$ t does_follow juanitofatas
No, @juanitofatas does not follow @JuanitoFatas.

$ t does_follow juanitofatas
No, @juanitofatas does not follow @juanitofatas.
```

After:

```
$ t does_follow juanitofatas
You cannot follow yourself!

$ t does_follow juanitofatas
"It's a same account!"
```