update the builder image

wanghaoran1988 · wanghaoran1988 · commit 8f2d44273320 · 2016-01-08T12:41:25.000+08:00
diff --git a/Dockerfile b/Dockerfile
@@ -1,4 +1,4 @@
-FROM openshift/ruby-22-centos7
+FROM centos/ruby-22-centos7
 USER default
 EXPOSE 8080
 ENV RACK_ENV production
