Remove abstract classes in order not to take in account.

Before this little change, Abstract classes were included in the list of classes to add into acos. 
So when later it does:
```php
$reflection->newInstanceWithoutConstructor()
```
it throws **Fatal Error Error: Cannot instantiate abstract class** when PHP version is >=5.4.
No error is thrown when PHP < v5.4, but it inserts Abtract class in acos table but never used, because it is odd to allow/deny permission in abtract classes.