add an observer to update signal lte and 4g icons (1/2)

  - remove the need for the systemui restart

Change-Id: I8bd2a660c2bd36f14d41b8e5cdea3e342bf4469f
Frameworks: option to hide singal bars (1/2)

Change-Id: If539d3452e23cb955b7b40175b8f52f60efd4ae0