Revert "Drop blacklist number uniqueness constraint."

This reverts commit 681b09afc57743e87aabb3556c88d2f8db7e0ca2.
Revert "Improve delete handling code."

This reverts commit ce2b3550a12acbaa9b01bbd660aa2c7a85ff55a6.
Revert "Store phone blacklist in content provider (2/4)"

This reverts commit 6cea074c67627c242af112c5dde552dfef5d32b5.