allow table object with no physical table

this allows by calling "$this->table(false);" to have an physical table
this you can use for example for login or contact or feedback form validation

```
public function initialize(array $config)
{
        parent::initialize($config);
        $this->table(false);
}
```

you could even do decimal validation by specifying the exact column type

for example:
```
public function initialize(array $config)
{
        parent::initialize($config);
        $this->table(false);
        $this->schema()->addColumn('length', [
            'type' => 'decimal',
            'length' => 10,
            'precision' => 2,
            'unsigned' => true,
            'null' => false,
            'default' => null
        ]);
}
```