#11 - strict public method parameter checking

[Ocramius]

Apologies for the branch name: I'm sleepy.

This PR introduces following behavior (providing implementation for #11)

class Bar {}
class Foo {
    /** @param $foo \Bar[] */
    public function doFoo(array $foo) {}
}

This will work:

$foo = new Foo();
$foo->doFoo([]);
$foo->doFoo([new Bar, new Bar]);

This will fail:

$foo = new Foo();
$foo->doFoo([123, 456]); // crash

Tests and SoC are still to be addressed, this is just a PoC.

@malukenho please review :D

TODOs:

• [x] documentation
• [x] unit tests
• [x] remove code duplication
• [x] proper dependency injection

[malukenho]

:beers: