Migration to CakePHP 1.3

CakePHP 1.3 is supposed to perform better, so this should speed up Tatoeba.

Please checkout this branch and thoroughly test it.

To check for migration bugs, I did a recursive download of both master and this branch, and then used `diff -r` to track changes. So I only carefully checked pages that are visible while being logged out. I only checked the logged in things with my eyes, and tested the usual POST actions for sentences, comments, tags, user profile and preferences, and the wall.