Phalcon\Db\Column type can be specified in a string

type processing is the same as TYPE_INTEGER (typeReference()).
type name is a `BIGINT` instead of `INT`.

``` php
new \Phalcon\Db\Column(
    'name', array(
        'type' => 'BIGINT',
        'typeReference' => \Phalcon\Db\Column::TYPE_INTEGER,
        'size' => 20,
        'unsigned' => true,
        'notNull' => false
    )
```

type name is `ENUM`.
specify the set value in typeValues().

``` php
new \Phalcon\Db\Column(
    'name', array(
        'type' => 'ENUM',
        'typeValues' => array('A', 'B', 'C'),
        'notNull' => true,
        'default' => 'A'
    )
```