go.blog: exclude gorilla example (fixes build)
go.blog: exclude gorilla example (fixes build)

Fix the build on builders that do not have git installed.

See discussion: https://groups.google.com/forum/#!topic/golang-dev/SAv_H7fJHkw

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/124890043

gorakhargosh/blog,jeffreyliguori/blog,gorakhargosh/blog