Store votes as percentage

The voting API value type for userreview ratings is VOTINGAPI_VALUE_TYPE_PERCENT, but they're on a scale of 0-10. This patch should fix that:

<code>480c480
<   $vobj->value = $node->vote_value;
---
>   $vobj->value = $node->vote_value * 10;
512c512
<   $vote->value = $node->vote_value;
---
>   $vote->value = $node->vote_value * 10;
731c731
<   $output .= theme('userreview_vote', $avg_vote);
---
>   $output .= theme('userreview_vote', $avg_vote / 10);

Old ratings will have to be upgraded.