java_gen: create OFFactory

first shot at factory interface for OF Objects. Will have to be
refined later.
diff --git a/java_gen/templates/_imports.java b/java_gen/templates/_imports.java
index 7700546..50ba198 100644
--- a/java_gen/templates/_imports.java
+++ b/java_gen/templates/_imports.java
@@ -1,7 +1,9 @@
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import org.openflow.protocol.*;
 import org.openflow.protocol.action.*;
+import org.openflow.protocol.meterband.*;
 import org.openflow.protocol.instruction.*;
 import org.openflow.protocol.match.*;
 import org.openflow.protocol.oxm.*;
@@ -10,3 +12,4 @@
 import org.openflow.util.*;
 import org.openflow.exceptions.*;
 import org.jboss.netty.buffer.ChannelBuffer;
+import org.jboss.netty.buffer.ChannelBuffers;