Nowadays a lot of frontend tools use source maps files (we do this in the new travel-demo too).

Unfortunately there is no MIME mapping defined in the server configuration resulting in log.infos:

2015-07-31 08:45:02,768 INFO  info.magnolia.cms.beans.config.MIMEMapping        : Cannot find MIME type for extension "map"

Suggestion

Add a MIME mapping config;/server/MIMEMapping/map with mime-type=application/octet-stream (see: http://stackoverflow.com/a/19912684).