Array validation with non iterative rules

Ok, one more PR related to Validator and its ability to validate arrays.

### How it works.

We have several additional methods in Factory and Validator:

Factory:
* setNonIterative()
* addNonIterative()
* removeNonIterative()
* getNonIterative()

Validator:
* setNonIterative() - not recommended in use (overrides default nonIterative rules)
* addNonIterative()
* removeNonIterative()
* getNonIterative()


These methods allow user to set/remove/view so called `nonIterative` rules. If currently validated rule is set in `nonIterative` array, then current value will be validated as a whole array (as it is), otherwise it'll be validated item by item if that value is an array but not present in `nonIterative`.

With default settings, Validator will work the same way as described in #255 PR. 
Except of several cases:
* `exists` rule will use "WHERE IN", so if value is an array there won't be tons of queries
* `same` & `different` will compare whole array with `other` attribute

Default `nonIterative`: `array('Exists', 'Same', 'Different')`.

### Add/Remove rules

Global:
````php
// sets new global non iterative array
Validator::setNonIterative('custom_rule');

// adds new rule to global non iterative array
Validator::addNonIterative('extra_rule');

// result: array('custom_rule', 'extra_rule');
````
Local:
````php
// $val - new validator class
$val->addNonIterative('custom_rule');
// or multiple
$val->addNonIterative(array('custom_rule', 'extra_rule'));
````

You can explicitly remove any rule from Factory and Validator:

 ````php
Validator::removeNonIterative('custom_rule');

// $val - new validator class
$val->removeNonIterative('custom_rule');
// or multiple
$val->removeNonIterative(array('custom_rule', 'extra_rule'));
````

In order to check which rules are set you can call `getNonIterative` (both on Factory and Validator class).

### Custom rules

If user creates custom validation rule via extends or just extends Validator class, then this rule will be validated on `per item` basis. You'll have to explicitly add your custom rule to the nonIterative array via `addNonIterative` on Factory or Validator class.