setTypeFace method for MaterialTab host

[swaheed2]

This helper methods can be very useful if you want to use font awesome icons as text for the tabs.

Example:

Typeface fontAwesome = Typeface.createFromAsset(getAssets(), "fonts/fontawesome-webfont.ttf");

    for (int i = 0; i < adapter.getCount(); i++) {

        MaterialTab tab = tabHost.newTab();
        tab.setText(adapter.getIcon(i));
        tab.setTabListener(this);
        tab.setTypeFace(fontAwesome);
        tabHost.addTab(tab);


    }

[felipebonezi]

Please, merge this pull request!
@neokree

[reixa00]

This PR should be merged. Take a look please. Well documented and simple change.

Thanks both!