Tethering: fix NPE when retrieving active interfaces

When in airplane mode getActiveNetworkInfo() may return null.

Change-Id: Icba37abb51b9378c8af73d9f6587e04c588dd85e
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
SystemUI: Update Ringer tile code.

Fixed the issue when ringer tile shows not correct ringer state.

Change-Id: Iddf7122d66a86caa032b026919857ccb0fa33497
VolumePanel: Don't force navigation bar

It always annoyed me that when changing volume while in immersive the navigation bar is shown.

Change-Id: I82bff7d22b741950ef26eaf092eb6272ab9ed7ff