Handle connections sending http_response

Certain misconfigured proxy servers send http_response packets. They typically look like 

    <0.19681.8077> CRASH REPORT Process <0.19681.8077> with 0 neighbours crashed with reason: 
    no case clause matching {ok,{http_response,{1,1},200,<<"OK">>},
    <<"Connection: Keep-Alive\r\nContent-Length: 12\r\nDate: Wed, 28 Aug 2013 19:25:52 GMT\r\n
    Access-Control-Allow-Origin: *\r\nVary: Accept-Encoding\r\nContent-Type: application/json\r\n\r\n">>}
    in elli_http:get_request/4 line 313


This patch handles such connections and ignores them.