Just like we do in the Budget module, and in some places in the Poll and
Legislation modules, we don't need to specify the class name when the
name of the relation matches the name of a class in the same module.
We use this method in two different scenarios. In an AJAX request, we
don't want to return every booth if the search is blank. However, in a
normal HTTP GET request, we want to return every record when the search
is empty, as we do everywhere else.
It's possible the behaviour of the AJAX call is unusual, since it
searches all booths, and not just the ones assigned to a poll. If we
changed this behaviour, we could simplify the code and remove the
`quick_search` method.
Some queries were accessing original column instead of the new
translatable one. This should have been causing unexpected behavior
for requests maded in a different locale than the application default.
