User picture is ignored.

Hi!

I have found ugly bug in gravatar.module function: gravatar_preprocess_user_picturem. When user sends picture, gravatar module ignores it and display avatar from their website.

it was:

    // Decide with picture to use.
    if (!empty($account->picture->filepath)) {
      $picture = $account->picture->filepath;
    }

it should be:

    // Decide with picture to use.
    if (!empty($account->picture->uri)) {
      $picture = $account->picture->uri;
    }