Allow defining DB adapter driver options

- Adds to the DB adapter input filter a validator for driver options
- Adds UI elements to the admin:
 - For new/edit screens, a collapse with the ability to add and remove option
   key/value pairs
 - For the view screen, a collapse with the ability to view options

These new UI features are intended to help support DB2 when used on IBM i Series hardware (AS400, etc). In particular, i Series requires options similar to the followign be specified:

```php
    'DB2' => array(
        'driver' => 'IbmDb2',
        'database' => '*LOCAL',
        'driver_options' => array(
                'i5_lib' => 'ZF2TEST',
                'i5_naming' => DB2_I5_NAMING_OFF
        )
    ),
```

By adding UI elements for specifying driver options, we complete the DB adapter support, making it more robust and flexible.