Plack::Handler::FCGI - Support Server::Starter

Support Server::Starter to allow hot-deploying in a defacto-standard manner.
It doesn't require Server::Starter module until SERVER_STARTER_PORT env is set.
Fix a bug that --manager option is ignored with Server::Starter
Merge pull request #435 from yuryu/master

Plack::Handler::FCGI - Support Server::Starter