Fixes `join` with related models which have "associative" conditions.

[albertboada]

Filtering for relations configured this way (associative conditions) was NOT working:

var $hasOne = array('Located' => array('conditions' => array(
    'Located.model' => 'Employee',
)));

Filtering for relations configured this way was working:

var $hasOne = array('Located' => array('conditions' => array(
    'Located.model = "Employee"',
)));

[lecterror]

Did you run the tests after this change? Do they still pass?

Sorry about (very) late reply :(