Fix QType Cast Double value to Integer value bug.

PHP Allows us to cast double values to integers quite easily. Assuming the double value to be ```4.4519452160494```, the following code will cast the value to 4:

```
$dblValue = 4.4519452160494;
$intValue = (int)$dblValue;
```

However, when we do:

```
$dblValue = 4.4519452160494;
$intValue = QType::Cast($dblValue, QType::Integer);
```
We get an error. This is because we are checking for only 'digits' in the number here : https://github.com/qcubed/framework/blob/master/includes/qcubed/_core/framework/QType.class.php#L155

The current change tries to fix this.