jupyter2: centering images just like jupyter
jupyter2: centering images just like jupyter

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