Include apt submodule

This is necessary for the required manipulation we use to add additional apt sources. Currently, this list includes only dotdeb, which lets us use some PHP versions that are used on WordPress.com but are not included in Ubuntu 12.04's repos.
Use PHP 5.4 to Match WordPress.com's Environment

To better mirror WordPress.com's deployment environment, utilize PHP 5.4 instead of PHP 5.3. Ubuntu 12.04 does not include PHP 5.4.x in any of its official repositories, so a third party PPA must be used.