use HTTP::HashServer instead of HTTP::Server::Simple in add_default_feeds test because it (hopefully) has better facilities for managing and killing children (the test on EC2 don't manage to kill a HTTP server sometimes)
remove "$SIG{ CHLD } = 'IGNORE'" from HTTP::HashServer because it mysteriously intercepts signals used by mediawords_web_store.pl (used by add_default_feeds.t); subroutine new() should instead kill the previous server before starting a new one by opening "/die"