Allow post none SSL field to Elavon

Problem/Motivation

Current implementation of commerce_elavon_request() only allow fields starting with 'ssl_' to be include in the request to Elavon. This will force merchant to define their custom fields start with 'ssl_' which is confusing with the SSL fields that already existed.

Current implementation:

foreach ($info as $key => $value) {
    // Keep keys starting by ssl_.
    if (strpos($key, 'ssl_') !== 0) {
      continue;
    }
    $sanitized_key = check_plain($key);
    $xmldata .= '<' . $sanitized_key . '>' . check_plain($value) . '</' . $sanitized_key . '>';
  }

Proposed resolution

Remove the restriction.

foreach ($info as $key => $value) {
    $sanitized_key = check_plain($key);
    $xmldata .= '<' . $sanitized_key . '>' . check_plain($value) . '</' . $sanitized_key . '>';
  }