Improve notification spam filter code.

- Follow coding style guidelines
- Replace dialog shown on click by adding the relevant information and
  the delete button to the item itself
- Minor layout tweaks
- Make the empty view more descriptive
- Add license headers

Change-Id: Ic685364087d6a093fdbb6a143a9c6ed78596b62b
Settings : Make proximity opt-in

Change-Id: Idfa64758a3c6d60ca4801f6f7f34f0429f95cbec

Conflicts:
	res/xml/display_settings.xml
	src/com/android/settings/DisplaySettings.java