Bug 976986 - SettingsListener should have unobserve() method
Merge pull request #16947 from dwi2/bug976986

Bug 976986 - SettingsListener should have unobserve() method
Bug 963556: Update NFC Manager, Handover to use new shared nfc_utils.js.
Bug 975268: [System][NFC] Reset the screen idle timeout when a NFC tag/device is detected.