Add Safety information to Settings > About Phone

The Safety information link is stored in a system property, ro.url.safetylegal

If the phone has data connection, select "Safety information" menu will open the
Safety information link.  If there is no data connection for the phone, a message will
pop up which ask user to open Safety information link from PC.

Change-Id: Ia46e2e868ebcda93138cb9f00c978d8ac827022a