Bug 1051793 - [CMAS] Plug in real CMAS input to the CMAS application

- Add cellbroadcast system message handler
- Removed unused styling and testing UI
- Add localization properties
Just thought, sometime it's when I look into SMS locale files it's hard for me to understand what this or another label is for. I was planning to experiment with smarter naming, like ```btn-ok```, ```btn-cancel```. What do you think?