SystemUI: Fix notification header disappearing on tablets

For some reason, the notification panel header has weird dimensions
when it has anything else than its original ColorDrawable as
background, and only on tablets.

We workaround this by not changing the drawable until requested.

Change-Id: Id76a5dcacf59c35b2e49681d6eeb4e828f7cbc58
Re-do contextual notification header images

PS2: morning
PS3: night
PS4: new night image
PS5: new morning image
----------------------After Rescue-----------------
PS6/4: Shift morning image
PS7/5: New Years image
PS8/6: New morning image (Credits: Lokesh Chamane)
PS9/7: Revert back to old morning image
PS10/8: new Christmas image

*I cropped these for the different resolutions instead of scaling. Let me know what you think*

Change-Id: I1f713f12b425dd63a98ec85f185606e36411c308
Add evening time to header

Change-Id: I5d9a41d92803d64f67cf2fb9dd2c4294a947efc3