Add PHP composer support

[maveius]

Could You add to feature list composer package manager support for PHP? Thanks?

Suggestions: I don't like ruby, but I think that I can to be your one of the contributors to add support for npm and composer. Thanks.

[epitron]

If you're interested in PHP and NPM support, the repl.it people stole my project's name and built a tool that's just for proglang libraries: https://github.com/replit/upm