Filter parameters config with expressions

This pull is related to https://github.com/doctrine/mongodb-odm/issues/899
It allows set filter parameters in config file.
Parse value parameter by [ExpressionLanguage](http://symfony.com/doc/current/components/expression_language/syntax.html)
OK, I've understood the problem about custom functions.

But what do you think about this case usage:
```yml
class: Doctrine\ODM\MongoDB\Query\Filter\SimpleFilter
    parameters:
        class: Acme\DemoBundle\Entity\User
        field: status
        # Entity class constant
        value: constant("Acme\\DemoBundle\\Entity\\User::STATUS_ENABLED")
```