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/intent/ErrorIntent.java b/src/main/java/net/onrc/onos/core/intent/ErrorIntent.java
index 31715a8..44ef6c3 100644
--- a/src/main/java/net/onrc/onos/core/intent/ErrorIntent.java
+++ b/src/main/java/net/onrc/onos/core/intent/ErrorIntent.java
@@ -1,7 +1,7 @@
 package net.onrc.onos.core.intent;
 
 /**
- * This class is instantiated by Run-times to express intent calculation error
+ * This class is instantiated by Run-times to express intent calculation error.
  *
  * @author Toshio Koide (t-koide@onlab.us)
  */
@@ -17,7 +17,7 @@
     public Intent parentIntent;
 
     /**
-     * Default constructor for Kryo deserialization
+     * Default constructor for Kryo deserialization.
      */
     protected ErrorIntent() {
     }