Previously h2load supports SPDY only for https URI. This is because
SPDY has no mechanism to negotiate its protocol version without NPN.
With this change, user can specify the exact protocol version to use
when http URI (without SSL/TLS) is used.
Supplying multiple URIs can simulate more real life situation on
server side. For example, we can supply URIs of html, css and js and
benchmark the server. The -m option is updated so that it defaults to
the number of supplied URIs.
Tatsuhiro Tsujikawa