Start 1.13 development

Change-Id: If6d7050776b9e4ee444990ed9e9baaa4c6cd8fe8

pom.xml

diff --git a/pom.xml b/pom.xml
index d4cc819..603e8b9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -21,7 +21,7 @@
   <groupId>com.google.gerrit</groupId>
   <artifactId>gwtorm</artifactId>
   <packaging>jar</packaging>
-  <version>1.12</version>
+  <version>1.13-SNAPSHOT</version>
   <name>gwtorm</name>
   <description>Tiny ORM</description>
   <url>https://gerrit.googlesource.com/gwtorm</url>