Fix cakephp, upgrade version, replace source code with composer download

This repairs cake php to a working state. It then replaces the 10MB of cakephp source code that is stored in our repository with a single composer dependency declaration file, and finally it upgrades cakephp to the latest release (from 2.3.0 to 2.5.7). Tested on vagrant and my personal travis queue: https://travis-ci.org/hamiltont/FrameworkBenchmarks/builds/44714756