Add Composer support

[RobLoach]

Composer is a package manager for PHP.

[scdoshi]

Also, thinking more about this, should js packages be managed by a PHP package manager. Seems like your worlflow should involve bower for js and composer for PHP.

Something like this: http://techportal.inviqa.com/2014/01/29/manage-project-dependencies-with-bower-and-composer/

[RobLoach]

@scdoshi This is mostly for situations where Bower or Node are not available for deployment. npm, or bower are fantastic for managing JavaScript dependencies, but not quite available everywhere. This is where Composer can help out.