java_gen/pom.xml: Bounce artifact version to 0.3.7-SNAPSHOT

For the API change in 078fcfd97
diff --git a/java_gen/pre-written/pom.xml b/java_gen/pre-written/pom.xml
index fd595ce..338172f 100644
--- a/java_gen/pre-written/pom.xml
+++ b/java_gen/pre-written/pom.xml
@@ -10,7 +10,7 @@
 
     <groupId>org.projectfloodlight</groupId>
     <artifactId>openflowj</artifactId>
-    <version>0.3.6-SNAPSHOT</version>
+    <version>0.3.7-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>OpenFlowJ-Loxi</name>