phpass

Weirdly, it seems that the SWCP server (running PHP 5.3.17) can't support password_compat, but it does support phpass, so we'll use that until PHP 5.5 is installed. Especially since I saw [Jeremy Kendall's neat tip to install papas with Composer](http://jeremykendall.net/2013/12/13/installing-phpass-from-openwall-via-composer/).