Fix of the bug that after selecting SIM slot
in which there's no card and trying to
enter PIN settings menu phone was getting
stuck in infinite looping between
PIN settings window and 'Cannot connect
to SIM card' popup.
1. Prepare Pure and Bell specific `Application`
classes and add them to `app` target:
- `products/BellHybrid/apps/Application.cpp`
- `products/PurePhone/apps/Application.cpp`
2. Update `CMakeLists.txt` files.
3. Move `ApplicationBell` implementation to Bell-specific
`Application` class and remove `ApplicationBell` files.
4. Change Bell apps parent classes from `ApplicationBell`
to Bell-specific `Application` class.
5. Rename `Application` to `ApplicationCommon` in the rest of the files.
