Friendship

Closes #2 
This line has multiple problems:

1. don't use parentheses in an `if`
2. it's too long (over 80 chars)
3. the `len` method should be used, not the property `len(my_list)`

You could write this better like:

```py
if Friendship.objects.filter(from_user=from_user, to_user=to_user).exists():
```