Add derby.log to .gitignore

This file seems to be generated by the tests.

Change-Id: I07a848df342dac5acb054065431dd1e6d3b718d3

.gitignore

diff --git a/.gitignore b/.gitignore
index 8762f06..5ce3d99 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+derby.log
 /target
 /generated_classes
 /.classpath