run Plack::Test on AnyEvent-based PSGI applications

 Plack::Test::AnyEvent allows you to easily test your AnyEvent-based
 PSGI applications. Normally, Plack::Test::MockHTTP or
 Plack::Test::Server work fine for this, but this implementation comes
 in handy when you'd like to test your streaming results as they come
 in, or if your application uses long-polling. For non-streaming
 requests, you can use this module exactly like Plack::Test::MockHTTP;
 otherwise, you can set up a content handler and call $res->recv. The
 event loop will then run until the PSGI application closes its writer
 handle or until your test client calls send on the response.