Add optional regulatory info page

Bug 7081675

If R.bools.config_show_regulatory_info is true, then show a "Regulatory
information" item on the "About phone" page. Show a DialogFragment
displaying the regulatory_info drawable if the item is clicked. Add a
1x1 blank regulatory_info drawable for devices that won't show this.

Change-Id: I5823d8969de038becf4911dce893dab5dbb23537