Add tablename to ar-single-table-inheritance

[dhoomm]

This prevents duplicate column names in joins.
class SportCar/HeavyCar extends Car the find function should also pass the table name to CarQuery

return new CarQuery(get_called_class(), ['type' => self::TYPE,'tableName'=> self::tableName()]);.

Then add a property $tableName to class CarQuery.
Then use it in function prepare as

$this->andWhere(["$this->tableName.type" => $this->type]);

When creating a join with a table having column name 'type' wont create conflict..

[Alexander Makarov]

Would you please make a pull request?

[dhoomm]

created at #148