Make sure AnimatorSet avoids null animations

This commit makes the animator set avoid null value animation objects
as much as possible. No comments about these have been expressed in
the documentation so they are just treated as being animations that
happen instantly and have no real effect meaning they are just
ignored. The null value checks are enforced in both the builder and
the extra helper commands allowing all the methods to receive null
values.

Change-Id: Icfd751b1abceccf7f1177680b86d30610471810e
Keyguard: Fix incorrect PIN entry on MSIM devices

This commit fixes a SystemUI FC caused by incorrect resource IDs that
happens on MSIM devices when the PIN code is entered incorrectly.

Change-Id: Iff82859e34018e84db1f8884019a53c3414b692b
Status bar activity indicators for mobile data and wifi

Google were nice enough to create xxhdpi drawables for us before removing them.

Reverts "Remove signal/wifi activity indicator icon overlays."

This reverts commit fcc901c10bffdfb9c6b31e676dec36b47d949979.

Included NetworkController.java modification from Iaaa556ffab3ed4be1da8016ed40d0a9c2efcde01

Adding preference for arrows

PS14: Fixing errors

PS15: Turning arrows off done via actual removing drawables work, so when arrows are turned off,
they do not redraw statusbar anymore :-[

PS16: Commit Iaaa556ffab3ed4be1da8016ed40d0a9c2efcde01 merged to this one

PS17: Rebase to allow merge with latest source

Change-Id: I7aa85f7c8442c45d17e42cac7823dfe93e3f24c1