Set new Melange version number to 2-1-20150426.

Change-Id: Iff53b0795c413e667732ccbd0ad381e234db7829
diff --git a/app/app.yaml.template b/app/app.yaml.template
index 2e2d839..4033dbd 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: 2-1-20150417
+version: 2-1-20150426
 runtime: python27
 api_version: 1
 threadsafe: false