User profile route

How does the route looks now:
```
https://code.co.ua/users/1
https://code.co.ua/users/2
https://code.co.ua/users/3
https://code.co.ua/users/...
```
How it should be:

(The user can choose a nickname, or system can generate uuid for him)
```
https://code.co.ua/@id3714
https://code.co.ua/@some-username
https://code.co.ua/@id1467
https://code.co.ua/@ostap
```

