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/devicemanager/OnosDevice.java b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
index 09dea03..f5a405d 100644
--- a/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
+++ b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
@@ -41,35 +41,35 @@
     private static int ACTIVITY_TIMEOUT = 30000;
 
     /**
-     * The MAC address associated with this entity
+     * The MAC address associated with this entity.
      */
     private MACAddress macAddress;
 
     /**
      * The IP address associated with this entity, or null if no IP learned
-     * from the network observation associated with this entity
+     * from the network observation associated with this entity.
      */
     private Integer ipv4Address;
 
     /**
-     * The VLAN tag on this entity, or null if untagged
+     * The VLAN tag on this entity, or null if untagged.
      */
     private Short vlan;
 
     /**
      * The DPID of the switch for the ingress point for this entity,
-     * or null if not present
+     * or null if not present.
      */
     private long switchDPID;
 
     /**
      * The port number of the switch for the ingress point for this entity,
-     * or null if not present
+     * or null if not present.
      */
     private short switchPort;
 
     /**
-     * The last time we observed this entity on the network
+     * The last time we observed this entity on the network.
      */
     private Date lastSeenTimestamp;
 
@@ -84,7 +84,7 @@
     }
 
     /**
-     * Create a new entity
+     * Create a new entity.
      *
      * @param macAddress
      * @param vlan