Fix #813 Blacklist uninteresting attributes.

Old trace.xml with minimal filtering:

    <step title="Incoming Request" 
        date="12/17 22:51:56" 
        url="/diagnostics/settings" 
        method="GET" type="request" 
        instance="3b789f" pid="1260,2,6" 
        Connection="Keep-Alive" 
        Accept="application/json" 
        Accept-Language="en-US" 
        Host="****" 
        Max-Forwards="9" 
        User-Agent="Azure-Portal/3.14.00296.29" 
        x-ms-client-request-id="****" 
        x-ms-client-session-id="ed199787-89b9-405e-9c79-3726b4604a04" 
        x-ms-principal-id="0003BFFDC3F88AB0" 
        x-ms-principal-liveid="****" 
        X-LiveUpgrade="1" 
        X-ARR-LOG-ID="7c4caefb-109d-4b27-9dd2-8ff1b3fd5af1" 
        DISGUISED-HOST="****" 
        X-Original-URL="/diagnostics/settings" 
        X-Forwarded-For="131.107.147.234:58186, 131.107.147.234" 
        X-ARR-SSL="1024|128|CN=*.kudu1.antares-test.windows-int.net|CN=*.kudu1.antares-test.windows-int.net"     
        elapsed="556">

New trace.xml with added filtering:

    <step title="Incoming Request" 
        date="12/17 22:55:27" 
        url="/deploy" 
        method="GET" 
        type="request" 
        instance="3b789f" 
        pid="3848,2,6" 
        Connection="Keep-Alive" 
        Accept="text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8" 
        Accept-Encoding="gzip,deflate,sdch" 
        Accept-Language="en-US,en;q=0.8" 
        Cookie="WAWebSiteSID=c33e7cf2ce374d05a4e5cdface4bc009; ARRAffinity=3b789f785018ddd1d5e0dc7bd5555fa3c719565bb93d7c53a29acd231df7493e" 
        Host="testheader01.scm.kudu1.antares-test.windows-int.net" 
        User-Agent="Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36" 
        elapsed="82">