Mysql driver: Changed from long term deprecation in 5.4 to deprecated in 5.5

Changed mysql driver deprecation information from planned long term deprecation in 5.4 to officially deprecated in 5.5. Source: http://us2.php.net/manual/en/migration55.deprecated.php. It's official :)
Merge pull request #364 from elliottb/patch-1

Mysql driver: Changed from long term deprecation to deprecated in 5.5