timestamp criteria for votingapi_select_votes and votingapi_select_results

Found that no results were being returned from votingapi_select_votes() and votingapi_select_results() when specifiying timestamp as part of criteria array. The API comments suggested that specifying a timestamp would return all records with a time larger than specified timestamp, however the resulting SQL query tried to do an '=' instead of a '>' resulting in an empty set. Proposed fix:

foreach ($criteria as $key => $value) {
if($key == 'timestamp' && !empty($value)) {
$query->condition($key, $value, is_array($value) ? 'IN' : '>');
} else {
$query->condition($key, $value, is_array($value) ? 'IN' : '=');
}
}

votingapi_select_votes() and votingapi_select_results() now return results when using timestamp in criteria array.