Use proper System Icon identifier for navring

Change-Id: I924fba4776e3953b572445d0701b92d6712e0e67
Do not show up navring on home longpress on navbar

if the user set a custom action on longpress

Change-Id: I659e15e7f9f28e0a0db020e414b99409742c5e2e

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java