Create a pluggable test web server interface

[mtdowling]

The test webserver is currently only implemented in node.js. Create a PHP implementation with instructions that can be run using a different web server (apache, nginx, php-cli, etc). Create an interface and PHPUnit configs for instantiating different test webservers.

[mtdowling]

On second though, I don't think this is needed. If you can't run the tests with node.js, then you can pass --exclude-group server to phpunit to not run the node.js dependent tests.