Fix entityvalidate property condition

Squashed commit of the following:

commit e351884bbba0f8797d7b5811e1efca2f93c39373
Author: Snir <snir@gizra.com>
Date:   Mon Sep 1 14:18:22 2014 +0300

    Fix condition.

commit d48cf4274d135565f0e8ae2df778716285d6d1b5
Author: Snir <snir@gizra.com>
Date:   Mon Sep 1 13:49:18 2014 +0300
Add \RestfulInterface::publicFieldsInfo() for declaring fields.

Use \RestfulInterface::getPublicFields() to get the processed fields (i.e. with default values initiazlied).
Make 'process_callbacks' recieve multiple callbacks.