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/flowprogrammer/FlowPusher.java b/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
index 8098792..b9b093f 100644
--- a/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
+++ b/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
@@ -136,7 +136,7 @@
         }
 
         /**
-         * Check if sending rate is within the rate
+         * Check if sending rate is within the rate.
          *
          * @param current Current time
          * @return true if within the rate
@@ -205,7 +205,7 @@
         }
 
         /**
-         * Check if this object has any messages in the queues to be sent
+         * Check if this object has any messages in the queues to be sent.
          *
          * @return True if there are some messages to be sent.
          */
@@ -939,7 +939,7 @@
     }
 
     /**
-     * Add message to queue
+     * Add message to queue.
      *
      * @param sw
      * @param msg