Phone: Display toast message for blank USSD request

As per spec 24.080, ussd response string should be
between 1 - 160.
When user requests SEND_USSD with blank/no
input, display toast message prompting user
to enter valid input.

Bug: 7471891
Change-Id: Ic7b7b89e8a683011048a19cabd1d36a27bbae953
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.

Change-Id: I0497dff62f5278da6bd5d441b8359294a9b2afd3

Conflicts:

	res/values-it/cm_strings.xml
	res/values/cm_strings.xml