Revert "Add gesture based lockscreen security. [1/2]"

This reverts commit 39f8d356fe85eab5e2dfd71d68dfc4c0663b663e.
NetStats: Add net stats to system bar.

PS2:
PS3:
Hide net stats view when notification area is disabled.

Change-Id: Ib35dd46b026dab00abe73966105806c54266e466

Conflicts:

	packages/SystemUI/res/layout/network_stats.xml
	packages/SystemUI/res/values/vendor_styles.xml
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.

PS2:
Keep track of screen on/off in a new field.

Change-Id: Ia131a0db65c4c762b7f28493e812f9fb21358a27

Conflicts:

	packages/SystemUI/src/com/android/systemui/statusbar/policy/NetworkStatsView.java