A fix for #36

There were some deprecated calls that I removed. That being said, these changes now create a more meaningful error that I'm still seeing #36 and still need help fixing:

```console
Symphony Warning: mysqli_real_escape_string() expects parameter 2 to be string, array given
```
```console
An error occurred in /Users/jdsimcoe/Sites/atheycreek/symphony/lib/toolkit/class.mysql.php around line 404
399 * The escaped SQL string
400 */
401 public static function cleanValue($value)
402 {
403 if (function_exists('mysqli_real_escape_string') && self::isConnected()) {
404 return mysqli_real_escape_string(MySQL::$_connection['id'], $value);
405 } else {
406 return addslashes($value);
407 }
408 }
```
```console
Backtrace
[:0]
    GenericErrorHandler::handler();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/toolkit/class.mysql.php:404]
    mysqli_real_escape_string();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/toolkit/class.field.php:334]
    MySQL::cleanValue();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/toolkit/fields/field.select.php:619]
    Field->cleanValue();
[/Users/jdsimcoe/Sites/atheycreek/extensions/xmlimporter/lib/class.xmlimporter.php:307]
    FieldSelect->buildDSRetrievalSQL();
[/Users/jdsimcoe/Sites/atheycreek/extensions/xmlimporter/content/content.importers.php:80]
    XMLImporter->commit();
[/Users/jdsimcoe/Sites/atheycreek/extensions/xmlimporter/content/content.importers.php:41]
    contentExtensionXmlImporterImporters->__prepareRun();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/core/class.administration.php:239]
    contentExtensionXmlImporterImporters->build();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/core/class.administration.php:442]
    Administration->__buildPage();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/boot/func.utilities.php:231]
    Administration->display();
[/Users/jdsimcoe/Sites/atheycreek/symphony/lib/boot/func.utilities.php:207]
    symphony_launcher();
[/Users/jdsimcoe/Sites/atheycreek/index.php:14]
    symphony();
```
```console
Database Query Log
[0.0001] SET character_set_connection = 'utf8', character_set_database = 'utf8', character_set_server = 'utf8';
[0.0001] SET CHARACTER SET 'utf8';
[0.0001] SET time_zone = '-07:00';
[0.0009] SELECT SQL_CACHE t1.name, t2.page, t2.delegate, t2.callback FROM `sym_extensions` as t1 INNER JOIN `sym_extensions_delegates` as t2 ON t1.id = t2.extension_id WHERE t1.status = 'enabled' ORDER BY t2.delegate, t1.name;
[0.0003] SELECT SQL_CACHE `session_data` FROM `sym_sessions` WHERE `session` = '34eaa6ea9a9e887fbb1e94f9474c4899' LIMIT 1;
[0.0002] SELECT SQL_CACHE a.* FROM `sym_authors` AS `a` WHERE `username` = 'jdsimcoe' ORDER BY a.id ASC LIMIT 1;
[0.0003] UPDATE sym_authors SET `last_seen` = '2014-09-18 15:45:20' WHERE `id` = 4;
[0.0004] SELECT SQL_CACHE `name` FROM `sym_extensions` WHERE `status` = 'enabled';
[0.0002] SELECT SQL_CACHE * FROM `sym_extensions`;
[0.0003] SELECT SQL_CACHE t1.* FROM sym_fields AS `t1` WHERE 1 AND t1.`id` IN(339);
[0.0002] SELECT SQL_CACHE * FROM `sym_fields_select` WHERE `field_id` IN (339);
[0.0002] SELECT SQL_CACHE `s`.* FROM `sym_sections` AS `s` WHERE `s`.`id` IN (29);
[0.0003] SELECT SQL_CACHE `id`, `element_name`, `type`, `location` FROM `sym_fields` WHERE `parent_section` = 29 ORDER BY `sortorder` ASC;
[0.0002] SELECT SQL_CACHE `id`, `element_name`, `type`, `location` FROM `sym_fields` WHERE `parent_section` = 29 ORDER BY `sortorder` ASC;
```

I get this error when trying to click "Run XML Importer".