ran composer update (after all it seemed travis started getting slow since yesterday independantly of this commit)

Revert 0dc425d0 as we notice System tests became much slower and also UI tests

Use latest doctrine/cache including file cache edge cases fixes. Add the alias repo to piwik composer.json so composer update will fetch this code.

The event dispatcher is needed for the Monolog Bridge

xhprof removed their composer.json file, adding it to our composer.json file so we can still use composer to manage xhprof. Added an extra script to make sure the update is clean for git users.

refs #5995 XHProf failed on PHP 5.3.10 on Ubuntu with a fatal error because those methods were private. Also one should rather execute composer install instead of update, otherwise one would update packages instead of installing the current defined versions