change default for unknown sources & verify apps

Change-Id: I04467c0c1ef3985b416f6e58013ddc3ce4137712
Make "SD Card removed" notification dismissible if the removed SD Card is not the primary storage

The Galaxy S uses the "external SD Card" as the extended storage
and it the notification should be dismissible as it's okay not
to have it.

Additionally, this patch also not hide the USB storage mount dialog
if the removed storage is not the primary storage

Adapted for CM 11

Change-Id: Ic752a3da917e0d7736a619fb68f07905106987fb
Add network usage stats to status bar (1/2)
PS2:
Get the time delta between updates and use that to show
average bytes per second.

Change-Id: I63771220333a32063f675e6fc38c9aadb6de4274
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
Network stats: Hide if there's no traffic (1/2)