Fix bug 5534667 - Action bar icons need more space on tablet

Set a wider minimum width for the action button style on -sw600dp.

Fix an annoying bug where recycled ActionMenuItemViews would retain a
lingering pressed state, causing an unrelated button to glow briefly.

The home/up affordance should not be focusable when it is disabled.

Change-Id: Ia68f3d09f5d977f50e4e33c354d8133367187973