midori does not allow non-http (e.g. socks) proxies

[gue5t gue5t]

midori_soup_session_set_proxy_uri checks if the proxy URI's protocol is http, and if not prepends "http://". It should only prepend a protocol if there is none. The current behavior breaks (in hostname resolution) "socks://"/"socks4://"/"socks5://" proxies, which have support otherwise.