Revert "Network stats: Hide if there's no traffic (1/2)"

This reverts commit 6730aa7012f5625a7c5827d43680e2cd08100bd7.
NetStats: Don't update stats when screen is off

Also moved registering of broadcast receiver and settings
observer to onAttachedToWindow() and unregistering to
onDetachedFromWindow() to avoid these being leaked.

Change-Id: Ia131a0db65c4c762b7f28493e812f9fb21358a27

Signed-off-by: MNT <m.zilius@gmail.com>
Network stats: Hide if there's no traffic (1/2)
Move networks stats systemUI style to stock file
network indicator - fix for: first time indicator was hidden auto when no traffic even if hide checkbox was not checked