Upgrade to Atomix 3.1.5

Change-Id: I1a46eb2ff22e15ab8c2ced8b327bdddb9ffd5017
diff --git a/tools/test/bin/atomix-push-bits b/tools/test/bin/atomix-push-bits
index 35ba9f5..79c762f 100755
--- a/tools/test/bin/atomix-push-bits
+++ b/tools/test/bin/atomix-push-bits
@@ -26,7 +26,7 @@
 
 . $ONOS_ROOT/tools/build/envDefaults
 
-ATOMIX_VERSION=${ATOMIX_VERSION:-3.1.0}
+ATOMIX_VERSION=${ATOMIX_VERSION:-3.1.5}
 ATOMIX_MAVEN=~/.m2/repository/io/atomix/atomix-dist/$ATOMIX_VERSION/atomix-dist-$ATOMIX_VERSION.tar.gz
 ATOMIX_LOCAL=/tmp/atomix-$ATOMIX_VERSION.tar.gz
 ATOMIX_REMOTE=https://oss.sonatype.org/content/repositories/releases/io/atomix/atomix-dist/$ATOMIX_VERSION/atomix-dist-$ATOMIX_VERSION.tar.gz