Added ability to set Image driver

[insane-dev]

Hi, thanks for your behavior :)
Maybe it would be useful to give ability to set Image driver?

Sometimes I have problems with Imagick library.
e.g. when creating thumbs it just shows white page, so if there is no time to fix this problem, it would be nice to have this option in your behavior.

I think it would be useful in other situations as well.

[mohorev]

Hello. I am opposed to the complexity of this behavior. If you have problems with Imagick - you can change Imagene driver property globally (in config or bootstrap file, for example).

/config/web.php

<?php

\yii\imagine\Image::$driver = 'gd2';

$config = [
    ...
    ...
];

return $config;

[insane-dev]

Well, yes you're right.