Gravatar

Title says it all really. After having another look at the code it looks like you can already do what I mentioned here like so:

foreach ($users as $user)
    echo $gravatar->email($user->email);

But I added the parameter to render() as it can't really do any harm.

Also changed form::attributes to html::attributes as form:: checks and sorts form field attributes, whereas html:: just compiles them.

Modified the getter / setter so that they can get / set config properties, attributes and the email address.