Fix block access checking when breaking block

Author: SBPrime

BlocksHub-GriefPrevention/src/org/primesoft/blockshub/accessors/bukkit/griefPrevention/GriefPreventionAc.java

@@ -161,7 +161,7 @@ public boolean canPlace(IPlayer player, IWorld world, Vector location,
 
         Location l = new Location(bWorld, location.getX(), location.getY(), location.getZ());               
 
-        if (airOld) {
+        if (!airOld) {
             if (m_griefPrevention.allowBreak(bukkitPlayer, new TypeOnlyBlock(blockOld), l) != null) {
                 return false;
             }