Refactoring (WIP)

Building from PHP Git source, is a great idea but it feels like pulling teeth from an angry crocodile with all the dependencies and specific versions (bison!?) that need to be stuffed into OSX – there must be an easier way!

This refactoring intends to fix this problem by: 
- Using a [clone of rbenv](https://github.com/createdbypete/phpenv) that has been re-purposed to PHP properly (I didn't like [this version](https://github.com/CHH/phpenv), it's a smart idea but for Boxen it could add complications). My repo will be tracking rbenv version releases and updating accordingly.
- Using [php-build](https://github.com/CHH/php-build) as this library downloads the tarball source, this does not require some of the more annoying dependencies such as a more recent bison version for > PHP 5.4.18 just to recompile something that already comes ready to go in the tarball.
- FPM should be a default in Boxen land as it is required to work with Nginx. This does not mean a load of empty fpm processes running just that PHP is compiled with FPM by default.
- Only support PHP 5.3.3 upwards because this is when FPM was included in the core. Require PHP any lower a version can be installed manually with custom options via `phpenv` but ask yourself why would you want to go any further back!? 
- General housekeeping and updating codebase to use any new definitions and maintain best practice as much as possible.

#### Extensions

- (WIP)Looks like [Pyrus](http://pear.php.net/manual/en/pyrus.commands.php) could be used to build and install our PECL extensions which would be useful/consistent.
- Xdebug available by default (due to php-build definitions installing it)
- Mcrypt compiled in by default (this is nearly always needed)
- Composer is available for per project deps such as PHPUnit (https://packagist.org/)