Add network usage stats to status bar: Re-implement for 4.4 [1/2]

Conflicts:

	packages/SystemUI/res/layout/status_bar_center_clock.xml
	packages/SystemUI/res/values/vendor_dimens.xml
	packages/SystemUI/res/values/vendor_styles.xml

Change-Id: I7c64a81167d0fea1ccd0adc9ed41e38fc07a79b7
Network stats: use number formating based on android code

Uses logic from Formatter.formatFileSize

Change-Id: I9008df0e90fbaf8d733cfd853dc1ef6160cf67f5
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Don't show Netstats when there's no traffic

Change-Id: Ie90caabd52dcfb6889cf26da37d7c57974993ffb