Set new Melange version number to 2-1-20150417.

Change-Id: Ide283a183e59d235b2abb8c03f637dd5b02695d3
diff --git a/app/app.yaml.template b/app/app.yaml.template
index 071f71d..2e2d839 100644
--- a/app/app.yaml.template
+++ b/app/app.yaml.template
@@ -15,7 +15,7 @@
 # TODO(proto): uncomment and supply a Google App Engine application instance
 # application: FIXME
 # TODO(release): see the instructions in README about the "version:" field
-version: 2-1-20150412
+version: 2-1-20150417
 runtime: python27
 api_version: 1
 threadsafe: false