Don't show notification count for a notification with just one item

For example, the Play Store sets the number attribute to 1 for a single
app update. No point in showing a counter for that.

Change-Id: I818622419f4f043fa8f04339ab24744aca7c1584
Merge "Don't show notification count for a notification with just one item" into kitkat
Merge commit '1ce97bfe09604740626c8523bb41a1e50e38e9fe' into kitkat
Merge "Don't show notification count for a notification with just one item" into kitkat