[checkpoints] minor: 8001, 8157 and 12311 checkpoints added.
[checkpoints] minor: 8001, 8157 and 12311 checkpoints added.

coinkeeper/terracoin_20150327,coinkeeper/terracoin_20150327,coinkeeper/terracoin_20150327,coinkeeper/terracoin_20150327,coinkeeper/terracoin_20150327