Phone: Add blacklist unknown numbers functionality
	This way you can choose to block numbers not
	in your contact list

	Add counters to missed and blacklisted calls
	notifications

Patchset 4:
	- Remove counters for a single call
	- Reformat
	- Move the dependency of the "unknown numbers" preference
	  under that of "private numbers", that is the logical
	  parent

Patchset 5:
	- Fix formatting

Patchset 6:
	- Solve a bug in which a private number would be blocked
	  as unknown, with the message "Unknown number: 0000"
	- Code the dependency between the two preference sets,
	  "Block private numbers" and "Block unknown numbers"
	- Make some code lines cleaner

Patchset 7 - 13
	- Some more corrections, spaces and tabs fixing.