Autodesk reorganized maya's modeling menu sets for 2015 in a way that more or less makes sense, however one thing they did away with was the keep faces together toggle box.
There are a couple of ways to get this back- In the preferences under the modeling section there is a checkbox for it, which is completely impractical
You can toggle it on and off after the fact in the channel box after doing an extrude for say, but like most people I like to plan in advance the type of action that I am doing so that is not the best choice
Note- when doing an extrude, you can shift+cntrl+right click to bring up a marking menu to toggle it as well
But if you want to have the old functionality back, I wrote a short script that you can use as a menu button to toggle it, and it will print on the command line if keep faces together is enabled or disabled
togglePolyMoveComponents;
int $faceState=`optionVar -q polyKeepFacetsGrouped`;
if ($faceState == true)
{
print ("Keep faces together ON");
}
else
{
print ("Keep faces together OFF");
}