disable checkpointing for security reasons

Further investigation of fast sync security is required

src/cryptonote_core/checkpoints_create.h

@@ -12,8 +12,12 @@
 namespace cryptonote {
   inline bool create_checkpoints(cryptonote::checkpoints& checkpoints)
   {      
-    ADD_CHECKPOINT(22231, "7cb10e29d67e1c069e6e11b17d30b809724255fee2f6868dc14cfc6ed44dfb25");
-    ADD_CHECKPOINT(29556, "53c484a8ed91e4da621bb2fa88106dbde426fe90d7ef07b9c1e5127fb6f3a7f6");
+    // Checkpointing disabled until we can make the client not fast-sync
+    // without checking PoW at some point. Otherwise we may be exposed
+    // to blockchain corruption attacks. Need to investigate this further.
+    // 8-5-14
+    // ADD_CHECKPOINT(22231, "7cb10e29d67e1c069e6e11b17d30b809724255fee2f6868dc14cfc6ed44dfb25");
+    // ADD_CHECKPOINT(29556, "53c484a8ed91e4da621bb2fa88106dbde426fe90d7ef07b9c1e5127fb6f3a7f6");
     return true;
   }
 }