bump version to 17.09.1-ce

Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>
diff --git a/VERSION b/VERSION
index 5b23dee..e4145de 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-17.09.1-ce-rc1
+17.09.1-ce