Telephony: "Add to blacklist" support to in-call ui (2 of 2)

Add back call blacklist backend.

              PS1: Blacklist Support
              PS2: Fix Compilation
              PS4: removes cm_string
              PS5: Use custom
              PS6: give it some love

Change-Id: Ia062f08a869ee9371a0778ebaabeb71ce76cbd2c