Print utility classes

Created by: gellmaster

Congrats on the 2.2.2 release and thanks to everyone that contributes.

Now that print css is included, what are your thoughts on adding responsive print utility classes? Easy enough to add to our individual projects but it may round out the printing features in bootstrap.

Maybe something like

.visible-print {
    display: none !important;
}

@media print {
    .visible-print {
        display: inherit !important;
    }

    .hidden-print {
        display: none !important;
    }
}