Enable checkstyle Javadoc Comment Style rule

Turn on the Javadoc Comment Style rule and fix
any violations that come up.  This is related to
requiring javadoc description comments to end
with a '.'

Change-Id: I19cf1b9f00d3040987e0b4c8b39461e2e0ad66b5
diff --git a/src/main/java/net/onrc/onos/core/datastore/utils/KVObject.java b/src/main/java/net/onrc/onos/core/datastore/utils/KVObject.java
index c696bd7..568cfc7 100644
--- a/src/main/java/net/onrc/onos/core/datastore/utils/KVObject.java
+++ b/src/main/java/net/onrc/onos/core/datastore/utils/KVObject.java
@@ -54,7 +54,7 @@
     private long version;
 
     /**
-     * Map to store user-defined properties
+     * Map to store user-defined properties.
      */
     private Map<Object, Object> propertyMap;
 
@@ -333,7 +333,7 @@
     }
 
     /**
-     * TODO Extract common interface
+     * TODO Extract common interface.
      */
     public static class WriteOp implements IMultiObjectOperation, IModifiableMultiEntryOperation {