Use gulp to minify javascript and json files under jekyll.

Change-Id: I5d46cb96d7b237103cf1973a77318833fc6ef2e5
diff --git a/.gitignore b/.gitignore
index badbc02..b4e9edd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 _site
 .sass-cache
+dist
+node_modules