Update User switcher to new spec, implement adding users

Also enforces restrictions on when guests can be added.

Bug: 15545213
Change-Id: Ia03747fbcc39f2b1b20876463c85afbac5057878
diff --git a/packages/SystemUI/src/com/android/systemui/qs/tiles/UserDetailView.java b/packages/SystemUI/src/com/android/systemui/qs/tiles/UserDetailView.java
index 67eef56..8cff81a 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/tiles/UserDetailView.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/tiles/UserDetailView.java
@@ -83,7 +83,7 @@
                     mContext, convertView, parent);
             String name = getName(mContext, item);
             if (item.picture == null) {
-                v.bind(name, mContext.getDrawable(R.drawable.ic_account_circle_qs));
+                v.bind(name, getDrawable(mContext, item));
             } else {
                 v.bind(name, item.picture);
             }