Settings: Network traffic (2/2)

@fusionjack:
* Option to show/hide network speed arrow icons
* Change checkbox to switch

Change-Id: Iad7825660ffeb15f2e89ea040cea3e664bb9a3a4
[2/2] Settings: Doze (ambient display) timeout

Patchset: put the preference in more sensible location.

Patchset: remove preference for devices that don't support
        doze display state.

Patchset: turn off doze timeout slider if doze is disabled

Patchset: move doze options to own preference category

Change-Id: I366a3a00bb48c20fa2d37f0b22fdbfeb3d004533

Conflicts:
	res/values/slim_strings.xml