Non intrusive incall ui, (2/3):

Thanks to OmniRom:
https://github.com/omnirom/android_packages_apps_Dialer/commit/682468375b15eba2366b5f4cffcc8223513fcf9b

- Enable/disable Non intrusive incall ui
- Click the back button to put the incall ui in the background
  (answer/dismiss the call from staus bar)