Cleaned up warnings reported by the Javadoc tool.

Javadoc reports warnings for things such as missing return descriptions,
missing or wrong parameters, invalid tags.

Note: I didn't touch any of the warnings in the OpenflowJ code.

Change-Id: I7234f617e092b489fad599196fc9cbe78f7e2db1
diff --git a/src/main/java/net/floodlightcontroller/core/module/IFloodlightModule.java b/src/main/java/net/floodlightcontroller/core/module/IFloodlightModule.java
index c616bc0..a0ee845 100644
--- a/src/main/java/net/floodlightcontroller/core/module/IFloodlightModule.java
+++ b/src/main/java/net/floodlightcontroller/core/module/IFloodlightModule.java
@@ -23,7 +23,7 @@
      * Return the list of interfaces that this module implements.
      * All interfaces must inherit IFloodlightService
      *
-     * @return
+     * @return a list of class objects of services the module implements
      */
 
     public Collection<Class<? extends IFloodlightService>> getModuleServices();