I've already changed the `ValidationException` so as not to let the file
and line from the Validator.php [1]. However, one could go even further
when creating more customizations on top of this library, and allowing
to customize the line could be very useful.
What motivated me making this change because it will be handy when I get
back to work on [Assertion][].
[1]: 75a9b8e94f
[Assertion]: https://github.com/Respect/Assertion
Because of how PHP works, when we instantiate an Exception object, the
`file` and `line` properties are the file and line where we created the
object. That's a desirable behaviour, but there's no value for a user to
know that we created an instance of `ValidationException` in the
`Validator` class.
This commit will overwrite the file and line in the
`ValidationException` to where the method `assert()` was called.
Note that when running `check()` it will still point to `Validator`, but
I decided not to change it, as the method `check()` got deprecated.
