webapp: disable detection of known users on landing page -- see #2051
webapp: disable detection of known users on landing page -- see #2051

tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,DrXyzzy/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,tscholl2/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc