Create an implementaion of IntentIdGenerator

- Define interface to allocate IdBlock in IdBlockAllocator
- Implement IdBlockAllocatorBasedIntentIdGenerator
- Refactor IdBlock class

Change-Id: I21fa21ae625e3d7e137a7f846bb5a0c1bdb8df9a
diff --git a/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java b/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
index 5bb7f00..5bff0e8 100644
--- a/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
+++ b/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
@@ -489,7 +489,7 @@
                 result = distributedIdCounter.add(range);
             } while (result == null || !result.succeeded());
 
-            return new IdBlock(result.preValue(), result.postValue() - 1, range);
+            return new IdBlock(result.preValue(), range);
         } catch (Exception e) {
             log.error("Error allocating ID block");
         }