update holder.js to v2.3; refs #12196
update less.js to v1.6.1 & use accurate filename; refs #12196
add Blob.js separate from filesaver.js

Blob.js version 2013-12-27 / 0055d054acbca43eff44fc25c891055440685d9c
Refs #12196
update to FileSaver.js version 2013-12-27 / 0055d054ac

Refs #12196
grunt dist build-customizer