Add profile to enable error-prone

- Execute following to manually run error-prone analysis in addition to
  regular static analysis:

    mvn clean verify -P error-prone -T 1C

  https://code.google.com/p/error-prone/

- Fix for detected error.

Change-Id: I32fe106e3b5dcfe1a08d1f284b1470a7c866dfb2
diff --git a/src/main/java/net/floodlightcontroller/core/internal/OFMessageEncoder.java b/src/main/java/net/floodlightcontroller/core/internal/OFMessageEncoder.java
index d61f17e..29916c8 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/OFMessageEncoder.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/OFMessageEncoder.java
@@ -48,7 +48,7 @@
         }
 
         ChannelBuffer buf = ChannelBuffers.buffer(size);
-        ;
+
         for (OFMessage ofm : msglist) {
             ofm.writeTo(buf);
         }