Add Mustache template library

The Mustache template library renders
Mustache (httP;//mustache.github.io) templates with Json contexts
produced by RapidJson.

Change-Id: I38fa33aea88bea7d19a2ee8cb548a50e3ca2f4a8
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/2196
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins